Well, if you don't know much about computers, like you stated about your partner and yourself, then don't delete files that you 'think' you don't need or 'think' are corrupt.
Seems like that since your partner 'got rid of' these files that you've had the problem. He has deleted important files which your computer needs to run smoothly!! And since you dont know what they are this makes the whole job of sorting this out alot harder!
Are the files he deleted still in the Recycle Bin, if so you can restore them!
Has your partner ANY idea of the names of the files he got rid of, as this will help
( An up-to-date Anti-virus scan will tell you of any files that are corrupt and remove them for you. Guess work can make a system go from working to a nightmare very quickly)
TIP OF THE DAY : Dont let your partner touch the computer