Windows problem, CAN YOU HELP?

I tried to download a program on limewire, and im guessing i downloaded some sort of adware or virus because when i tried to open the program i immediatly had my computer shut down on me. then when i was online and wanted to do to a website it would re-direct me to marketing websites. this is a mess. now when i try to get on to windows it says "windows has discovered a change that will result in limited Windows functionality. Use the link below to find out how to fix windows." When I go to the link it is a website that doesnt help one bit. I was messing around on my internet explorer options and seemed to have messed things all up as well. I cannot access any of my programs or files, all i can do is go on internet explorer...barely. If i try to find something on a search engine and go to click to the link to the website it always brings me to a websiite that isnt even working. Please help! Im desperate...is there a way to restore my old settings, or re install windows without disk. HELP!!!