Oh man this is bad

i think i killed it. my car wont go in drive anymore it only goes in reverse...did i f**k my transmission or is it something minor?

You will have to be more specific. If the shifter works OK and it has fluid, it doesn't look good.

well...there is fluid in there i know that and theres oil all over my air filter and inside of that big round thing. see, i let somebody drive it and this is the condition i get it back in...

NEVER loan your car to anybody. If you think people are hard on rental cars (that people pay to use), imagine the abuse you get when they don't have to pay anything.

Pull the transmission dipstick, read what it says (check hot, engine at idle, in park). If you don't see any fluid OR the fluid you see is dark, smells burned or like varnish - you are hosed.

If your cooling system problem wasn't fixed right, the trans fluid could easily cook if the radiator is the only source of cooling.

There is a SLIGHT chance that the filter got clogged with crap and is keeping the valve body from getting the fluid it needs to operate in forward.

Let us know what happens, and how much prison time you have to do for beating the crap out of the dude that ruined your car.