If you need help, please contact Apple Support. The importance of regularly backing up your computer cannot be overstated.
Click Continue to start the transfer. Large transfers might need several hours to complete.
If you replace, the old account will delete and then replace the account on your Mac, including everything in its home folder. You should now see that Time Machine has a backup location, and Select Disk shows the proper name of the sparsebundle. If you rename, the old account will appear as a separate user on your Mac, with a separate home folder and login. Check Time Machine Now we need to check that Time Machine sees the Disk and is ready to use it for backups. In this example, John Appleseed is a macOS user account. If it has the same name as an account already on your Mac, you're prompted to either rename the old account or replace the one on your Mac.
Select your Time Machine backup, then click Continue.
When asked how you want to transfer your information, select the option to transfer from a Mac, Time Machine backup, or startup disk.
If your Mac starts up to a setup assistant, which asks for details like your country and network, continue to the next step, because the setup assistant includes a migration assistant. It's in the Utilities folder of your Applications folder. The first approach, since you can access Time Machine backups from within Mail, is to go to your mailbox in Mail and then invoke Time Machine and attempt to find and restore your messages from within the Mail interface however, this is only practical for recovering a few messages, and in some cases this approach may simply not work.
Make sure that your Time Machine backup disk is connected to your Mac and turned on.
For example, if your Mac starts up to a flashing question mark, you need to first reinstall macOS.
If you need to reinstall macOS, do that before continuing.