If something went wrong and you lost some files and documents, you can restore from a recent backup (if you have one).

If you simply copied your files to a safe location, such as an external hard drive, another computer on the network or a USB drive, you can copy them back to your computer.

If you used Déjà Dup (or some other backup application) to perform your backup, you should use Déjà Dup to restore your data from backup too. See the help for Déjà Dup for more information.