Log in to Directadmin. If you are not sure how to get here, you can look in this guide.

Navigate then to Extra Features -> Installatron Applications Installer

Then press My Backups and select the backup you want to run. Then click the arrow:

Then select Restore to Original location to restore to your previous backup.

Here are shown which files are restored and overwritten. Then click restore to restore to a previous backup.

It may take some time depending on how large the files are to be restored. Once it has finished loading, everything is restored to your backup.