Its up to you OP what you do....
I generally dont use Restore Points reason being, having had the unfortunate experience where a virus/trojan has bypassed the anti-virus system and infected the computer, have found on occassions that also the Restore Points were infected which basically means the only cure is a complete format (including Master Boot Records) and Fresh Re-install.
I think we do Differ on the understanding of what the OP is saying, in your version I would say you are correct it could fix it.
My version of understanding is that the files/emails have gone to Never Never Land, if you like An Alternate Universe with-in their computer. ie not deleted maybe not even missing just invisble, hiding some where between the other files.
The reason I suggested Recuva (whether it works for the OP or not only the OP can try to find out) is that instead of just looking at restore points, restore point logs, previous version logs and rebuilding files.
Recuva is more forensics based not quite like FBI CIA or the police level forensics, but it tries to look between the files, round defrags, file deletions, formats and those Never Never Land Areas.
I'll agree success can be hit or miss, but email/word documents should be a hell of a lot easier to recover than audio and visual (movie) files......... - believe me you really dont want to try and recover 500-600gigs of movie files it will take you years.
Best bet before use though is to have a blank USB stick/ hard drive with alot space to save the results. and it may need to be run several times.