Snapshot restore a website

Hi I have a multisite and I used snapshot to back it up.

today I run into some problem with the site that stop showing me pages in the wp admin area and I don’t know why. for example If I click to the appearance widget page the page is not showed??? so I decided to restore the previous version that was working just fine.

I can not find the right info on how to perform a full restore with snapshot.

could you please direct me to some king of info or tell me the step by step process? to be clear I can not even access to the plugin page at the moment.

thanks.

Luca