First thing to do is a search for a file name for one of the missing files.
If that fails to show up then you can run recovery programmes FROM A DIFFERENT DISK and see it the missing files are still in existence (don't save anything more to the disk).
If that fails you can write them off as an experience learnt.
One could be more sure of a legitimate answer with more info than "I updated my computer". That could mean you traded it in for a faster model, even.