Hey there Mari.K,
Thanks for reaching out to the Apple Support Communities.
Based on the information you've provided, you can find some helpful steps that can walk you through troubleshooting issues with restoring a Time Machine backup at the links below:
- Make sure that you're using a backup disk supported by Time Machine.
- Unless you're using a network backup disk, make sure that your backup disk is connected directly to your Mac, not through a USB hub or other device.
- If your backup disk is connected directly to your Mac, use Disk Utility to repair the disk.
- If you're using a network backup disk, make sure that the network connection is good and your Mac is connected to the same network as the backup disk. If you completed a previous backup successfully, verify that backup: Press and hold the Option key while choosing Verify Backups from the Time Machine menu in the menu bar.
- Make sure that the firmware of your backup disk is up to date. Check with the manufacturer of the backup disk for details.
- If your backup disk is connected to your Mac, make sure the disk is firmly connected, plugged into a power source, and turned on.
- If your backup disk is connected to a network, make sure your Mac and disk are still on the same network, the disk is turned on, and the network isn’t experiencing problems.
- If your backup disk is connected to another computer, make sure the computer isn’t in sleep mode. If it is, disable the sleep function for future backups.
- Open Time Machine settings and reselect your backup disk. If you erased your backup disk and began having trouble, reselecting it may fix the problem.
- If you’re using a Time Capsule as your backup disk, use AirPort Utility to make sure it’s set up properly and connected to your network.
- Click the Finder icon in the Dock to open a Finder window, then look in the Locations section. Your backup disk should be listed. If it’s not, it may be turned off, defective, or currently unavailable on the network.
- If you back up to a Time Capsule or other network disk that has a password, the password may have changed. Log in to your Mac as an administrator, open Time Machine settings, reselect the backup disk, then enter the new password.
For a list of additional resources that can further troubleshoot Time Machine related issues, take a look at this next resource: Time Machine troubleshooting on Mac - Apple Support.
Keep us updated on the results.
Best regards.