My car won't start. It sounds like its going to but it doesn't.?

All of the accessories light up and i tried to give it gas but it didn't do anything when i did that. I'm gonna take it to the shop this weekend. I want to get an idea of what it could be and how much I could be spending. I have a 2003 cadillac cts with over 78,ooo miles. Oh yeah, engine light had came on prior to that. Any ideas?