What a complete restart means and when you need one

A complete restart — also called a factory reset or clean install — wipes your hard drive and reinstalls your operating system from scratch. This is different from a normal shutdown and restart, which just closes your programs and boots back up with everything still there.

You need a complete restart when your computer has become slow, unstable, or infected with malware that regular fixes cannot remove. It is also the right choice before selling or giving away a device, because it removes all your personal files, passwords, and browsing history permanently. A complete restart takes one to three hours depending on your internet speed and which operating system you use.

Before you start, understand that this process deletes everything on your computer. Back up any files you want to keep — photos, documents, downloads — to an external drive or cloud storage first. Once you restart, those files are gone.

Key Takeaways

  • A complete restart erases your entire hard drive and reinstalls Windows or macOS from the beginning, which takes one to three hours.
  • Back up all your files to an external drive or cloud storage before you start, because the process deletes everything.
  • On Windows, use Settings > System > Recovery > Reset this PC, which lets you choose whether to keep or remove your files.
  • On Mac, restart into Recovery Mode by holding Command + R during startup, then use Disk Utility to erase and reinstall macOS.
  • After the restart completes, you will need to sign back into your accounts and reinstall your programs one by one.

How to restart Windows completely

On Windows 10 or Windows 11, the Reset this PC tool is built into Settings and does not require a separate installation disc. Open Settings by pressing the Windows key and typing "settings", then click System in the left sidebar. Scroll down and click Recovery, then click Reset this PC.

Windows will ask whether you want to Keep my files or Remove everything. Choose Remove everything if you want a truly clean slate — this erases all your programs, settings, and personal files. Choose Keep my files only if you want to remove programs and malware but preserve your documents and photos. Either way, Windows will reinstall itself fresh.

The process will restart your computer automatically and may take 30 minutes to two hours depending on your internet connection. Your screen will show a progress bar. Do not turn off your computer during this time. When it finishes, you will see the Windows setup screen asking for your language and region, just like a brand-new computer.

How to restart Mac completely

On a Mac, you restart by erasing the drive and reinstalling macOS using Recovery Mode. Shut down your Mac completely, then turn it back on and when ready hold down Command + R. Keep holding until you see the Apple logo or a spinning globe. This boots into Recovery Mode, a separate system that lets you manage your hard drive.

Once in Recovery Mode, click Disk Utility in the Utilities window. Select your main drive (usually called Macintosh HD) in the left sidebar, then click Erase at the top. A dialog will ask for a name and format — leave the name as Macintosh HD and keep the format as APFS, then click Erase. This wipes the drive completely.

When the erase finishes, close Disk Utility and you will return to the Recovery Mode menu. Click Reinstall macOS, then follow the on-screen steps to read and install a fresh copy of your operating system. This takes 45 minutes to two hours depending on your internet speed. Your Mac will restart several times during the process.

Backing up your files before you restart

The safest backup method is an external hard drive. Plug in a drive with enough space for all your files — most people need 500 GB to 1 TB — then copy your Documents, Pictures, Downloads, and Desktop folders to it. On Windows, you can also use File History in Settings > System > Storage > Advanced storage options. On Mac, Time Machine in System Settings > General > Time Machine will back up automatically if you leave the drive plugged in.

Cloud storage like Google Drive, OneDrive, or iCloud also works, but uploading large amounts of data can take hours. If you have a slow internet connection, an external drive is faster. If you use cloud storage, sign into your account on the cloud service's website and read your files to your computer first, then transfer them to the external drive as a backup.

Check that your backup actually contains your files before you restart. Open the external drive or cloud folder and spot-check a few important documents. If the backup failed, you will not know until after your restart, when it is too late.

What happens after the restart completes

When your computer finishes restarting, it will look and feel like a brand-new device. You will see the setup screen asking for your language, region, and Microsoft or Apple account. Sign in with the same account you used before — this lets you read your settings, some of your apps, and your files from cloud storage if you saved them there.

Your programs are gone and must be reinstalled one by one. If you use Microsoft Office, Adobe Creative Suite, or other paid software, you will need your license key or login to reinstall them. Free programs like Chrome, Firefox, VLC, or 7-Zip can be downloaded again from their websites. This is a good time to uninstall programs you no longer use instead of reinstalling them.

Your files from the backup can be copied back from the external drive or downloaded from cloud storage. Do this slowly — copy a few folders at a time and make sure they appear correctly before copying more. This prevents one corrupted file from ruining your entire backup.

When a complete restart might not be necessary

If your computer is just slow, try these steps first: restart normally, uninstall programs you do not use, delete old files from your Downloads folder, and run Windows Defender (Windows) or Activity Monitor (Mac) to check for malware. These fixes take 30 minutes and often work without erasing everything.

If your computer has a virus or malware that will not go away, a complete restart is the most reliable fix. Malware can hide in system files where regular antivirus software cannot reach it. A complete restart removes it completely because the operating system itself is reinstalled fresh.

If you are selling or giving away your computer, a complete restart is the only safe way to remove your personal information. straightforward deleting files does not erase them — they can be recovered with special software. A complete restart makes recovery impossible.

Troubleshooting if the restart fails

If your restart stops partway through or shows an error message, try restarting the process again. Most failures are temporary — a network hiccup or a file that was in use. Restart your computer normally, then go back to Settings > Recovery > Reset this PC (Windows) or Recovery Mode (Mac) and try again.

If the restart fails multiple times, your hard drive may be failing. On Windows, open Settings > System > Storage and look for a message about drive health. On Mac, restart into Recovery Mode and open Disk Utility, then click First Aid to check the drive. If Disk Utility reports errors it cannot fix, the drive needs replacement before you can restart.

If you cannot restart because your computer will not boot at all, you may need a bootable USB drive with Windows or macOS on it. This is more complex and usually requires help from a technician or a detailed guide specific to your situation.

Frequently Asked Questions

Will a complete restart remove viruses and malware?

Yes. A complete restart erases everything on your hard drive and reinstalls the operating system fresh, which removes all malware, viruses, and unwanted programs. This is the most thorough way to clean an infected computer. Regular antivirus software cannot always find malware hidden in system files, but a complete restart removes it completely.

Can I restart my computer if I forgot my password?

Yes. On Windows, you can restart without signing in — just choose Remove everything during the reset process. On Mac, you need to restart into Recovery Mode, which does not require your password. After the restart completes, you will create a new account and password during setup.

What if I restart but my computer is still slow?

Slowness after a restart usually means you are reinstalling the same programs that were slowing it down before. Avoid installing programs you do not actually use. If slowness returns after a few weeks, your hard drive may be failing, or you may have installed malware again. Check your hard drive health in Settings or Disk Utility.

How do I know if my backup worked before I restart?

Open your external drive or cloud storage folder and look for your important files — a few documents, photos, or downloads. Click on one and open it to make sure it is not corrupted. If your files open normally, your backup is good. Do not restart until you have checked at least three files.

Do I need the Windows or macOS installation disc to restart?

No. Windows 10, Windows 11, and modern versions of macOS can restart without a disc — the reset tools are built into the operating system itself. The only time you need a disc or USB drive is if your computer will not boot at all, which is rare.