Sorry, I just saw this ... DLL files are "Dynamic Link Libary" files that execute commands when you ask your computer to do something. Maleware and spyware can effect your dll files and make stuff STOP working.
I would have suggested you restart in safemode then click on RUN and enter "cmd" then type: chkdsk /r
If that didnt do it, install Malwarebytes and run it in safemode w/ networking. Then install Spybot 1.6 and run it too. It would have saved your files ... (oooops).
Maybe I should PM you my phone number "just in case"!!!!