Theme and Windows Unexpectedly Changed

Hello,
I recently got my laptop running vista home x32 and have had it for about 2 weeks now. Just recently (I cannot pinpoint the exact time) I have had numerous changes appear to the appearance of my computer. They follow as:

Window color has changed from back to light blue
Alt tab window changed to simplistic ugly window
Can no long windows-tab between programs
Icons on desktop become pixelated
Icons in general more pixelated
Inability to alt-tab out of games
No longer receive a 'preview' of the program when mouse hovers over in task bar

I have no clue why this has happened. I've tried restoring my theme back to default but to no result. I've ran virus scans etc and nothing has showed up. Any ideas as to why all this would happen?



EDIT: I think this is because i'm not running aero, but I think I accidentally deleted it going through old themes
How can I get it back?

The first 2 things maybe aero is off..
When aero is off the theme is a light blue and the ALT-TAB background stop's being transperent

Definitely deleted. It's no longer in the drop down menu. I'm such an idiot. I'm looking through my drivers now. Is there a website that might have it?

Okay never mind I found out what was wrong. Had some options I needed to change in my appearance. Thanks for the help anyways haha. You may close this thread.