I was too busy to get around to working on my sticky so it is far from ready. I will try to finish it soon but it might be a bit too late in the game for you so let me just tell you this:

Do NOT go berserk like your PC and do a whole bunch of things in random just to 'fix' the problems. When it comes to spyware or registry cleanup, you have to follow a certain procedure, you can't rush things and more importantly you have to do one thing/use one program at a time so it would be easier to recover from unexpected problems occuring from each work.

As far as recovering/reverting back the changes you had done so far goes, what have you done to backup the system or the registry?
If you can't even remember what you have been doing the last few days or the last thing you had done prior to the problems started occuring, you are pretty much SOL on resolving the problem and it would definitely not making it easy for even an expert who is trying to help.

Spywareand AV scanners are only as good as their definition files for the most part. Even if they help cleanup an infected system, they can NOT help repairing or replanishing the missing/corrupt system files and/or registry values...

I will try to follow up but you have to provide the details on what you have been doing to your system all this time. You can't say "I did all the spyware scanning and defragging...' that is not enough detail but if that is literally what you have done, it sounds inadequate to say the least and still, you have to disclose what scanners you ran, what they found, what they could fix/couldn't fix, etc.

Remember (this goes to all those crying for help):

Better (exact wording, details, screenshots, whatever is possible) the info you provide, better the help you will receive!
You must take time and do things properly when working on a PC problem, you can't rush things.
Taking the PC to a nearby computer shop might be a good thing, it all depends. We are here to help the best possible way but know the limitations of free online help!