My car turns on but doesnt run at all what could be wrong with it??

What is your question?

My car started running really slow a few weeks ago so i took it to the dealer i bought it from and they told me that it was just a oil leak and that they had fixed it. I payed $250.00 dollars just for that. Now the car stoped running while i was driving to work. I turns on just fine but it doesnt move at all. What could hace caused this?? Someone please explain it to me and how muchos $$ are se talking about?