Hi everyone - I'm new to the forums here

I'm unsure if this is the right place to put questions about viruses - if im wrong sorry.
I'm posting from a hideously infected PC, and I havn't got a clue how to fix it.
Recently I have been downloading a good bit. Everything seemed fine until a warning popup from windows defender saying something ( I can't remember- sorry) about a trojan. I chose the option that said delete. Everything worked normally again. I use opera internet browser, but I have IE as well. Anyway i was using opera - and just out of the blue IE popped up and closed itself again. Now I cant open IE at all - the same thing keeps happening. I shut the computer down saying that I'd look at it later. Or more i tried to shut it down. Every time i clicked shut down - nothing happend! I restarted the computer and it did restart. However as soon as I got to the login part, A box popped up saying the computer was going to shut down in 60 seconds, because there was an error with c:\WINDOWS/system32/services!
For a while i couldn't log on at all it ept shutting down before I could do anything. During one startup I hit F12 to enter the menu thing - changed nothing and went back to startup and for some reason the countdown timer did not appear. I logged on - however the only thing that came up wass my background. This has happened to me before - normally i just start task manager go new task type in explorer.exe and it comes up again. Ohhh no. NOW it says i dont have appropriate permissions to access this file!
One thing i can do now tho is start task manager/new task /Browse find opera and run it to find out what to do - i found a website that said donwload autoruns to find viruses. I downloaded autoruns and extracted it to C:\Autoruns then it said restart in safe mode. I ran msconfig and did so. The computer restarted and got up to the login screen - where it normally has the users of the computer - Administrator was there this time? I don't know if that is simply what happens in safe more or not. but anyway I tried to log in as admin - but it asked me for a password? I had no clue... So i left it. And loged in as myself. The website then told me to locate autoruns.exe in C:\ drive i did it. And the program ran for about 5 seconds then closed unexpectedly. I tried to open it again but THIS time it said i didnt have the PERMISSION to???
I feel like crying. If anyone can help me by even telling me what exactly is goin on it would be much appreciated.
THANK you for your time,
Owen
P.S. I did a system restore to the point before I downloaded everything and its still screwed