I found out that the transmission oil cooler had snapped so I replaced it now the car starts but when I shift to drive or reverse it goes back to park if there is no transmission fluid or if its low would that cause this problem any advice thanks

 

That sounds odd. 2009? Take it to the dealer.

 

 

I had an accident and hit the right side of the car broke the headlight bumper and the transmission oil cooler broke too and leaked oil but I fixed all that if I take it to dealer they will every possible way to rob me but the mechanic at BMW told me to put oil

 

Could be a software issue. What happens when you shift into D?

 

when i put in D or R it goes back to P and says fluid something visit the shop.

 

Did a "qualified" shop repair your 2009 BMW ?? I sure hope you didn't band-aid a $60,000 car trying to save a couple of dollars

 

No I changed the headlight hood fender and the trans cooler so the work is done right going there Monday to put some trans oil so freaking expensive hoping that would fix it

 

so you had a leak, and repaired it, but didnt add any fluid? if not, then that is most likely your problem. auto transmissions are hydraulicly operated and they dont work when low on fluid.
you need to raise the car and fill the transmission through the fill plug on the side of the transmission, while the engine is running, and fill until fluid comes back out. there should be a how-to somewhere on this site, if you search.

 

You need fluid lol...if you drained it and did not replace it...thats most likely the problem. Was the accident your fault? What happened?