Windows 8 Need immediate help.

So first of all I will apologize for my English since it's not my mother language.Now to the main topic.Today I woke up and when I opened my pc it had trouble with the audio.I thought hmm maybe my headsets are broken or something , so I plugged in x2 new set of headsets but none of them were working ,even though they were working in my other PC and laptop.So then I troubleshooted the audio thingy and it said that one of the services , either Windows Audio or Audio End Point Builder are not working.Then I click on the "look for more help" and it lags.I am like what the heck.Then I open my control panel and it lags aswell.By lag I mean it just won't show me anything and I just can't click on anything aswell.Then I run my 2 antiviruses first YAC(Yet Another Cleaner) and AVG(free edition) and they don't work aswell.From all of this I got 1 error from AVG that it said something about another user inteferring with the process.Now my question is , what is the possibility that another user got access into my windows user account and what can I do to fix things.
PS:It's not that bad , I mean I only have problems with the audio(which is not working , AT ALL) and with anti viruses.I am just a 18year old kid so I don't have anything of value either in my windows account or my personal data.