i literally copy and pasted ur question into google and clicked the result. Here it is:
Try again after each step
- Make sure your Mac or PC is up-to-date. If you're using iTunes, make sure that you have the latest version of iTunes.
- Connect your device to your computer with a USB cable, and locate your device on your computer. If your device doesn't appear in Finder or iTunes, learn what to do. If you forgot your passcode or your device is disabled, learn what to do.
- Restart all your devices.
- If you use a Mac, skip this step. If you use a Windows PC and iTunes won't respond or your backup never finishes, you might need to update, change, disable, or uninstall your security software.
- If you own more than one computer, try to make a backup on your other Mac or PC. Or, use iCloud to back up your device and restore from your iCloud backup.
- If you see an alert that says an error occurred, your backup is corrupt or incompatible, or there's not enough disk space, find your error message below to learn what to do next.
- Contact Apple Support.
If an alert says that an error occurred
If a message says that your computer can't back up your device because an error occurred, check that you have the latest version of iOS or iPadOS. If you need more help, contact Apple Support.
If an alert says there's not enough disk space
If a message says there’s not enough disk space when you try to back up your device, free some space on your Mac or PC. If you still see a disk-space error after you free enough space, contact Apple Support.
If an alert says that your backup is corrupt or incompatible
If your iOS or iPadOS device can't restore from a backup because the backup is corrupt or incompatible, make sure that your computer is updated. If you see an error that says your iOS or iPadOS software is too old, find out how to update your device to restore the backup. If you still can't restore the backup, you might not be able to use that backup. Try to use an alternate backup or an iCloud backup, or Contact Apple Support for more help.