Vista problems please help!!?

ok i swiched to vista to get my game fixed it work but i didnt have a genuine product key so now all the options are use the atometed phone system acces your computer with reduced fuctionality and buy product key online or type a differnt product key i tried contacting microsoft but there just like if you would lke to chat with us it will cost 45$ id ont have that money to do that please helpi want xp back or a product key if u can give me one but thanks for your help and who ever helps me fix my computer will get 5 stars and best answer