Depends on the kind of backup really

Just a folder full of duplicate files? Try to open them.

Having a drive image you can restore from? Take an extra drive and try to “restore” the contents of your backup onto it. You use the extra drive because if you just use your primary drive you may brick yourself.

There’s definitely types of backups I’m not covering here but you should do research into the type of backups you want to use and the restoration process, and basically try the restoration process intermittently.