How can i fix my 2004 Ford Explorer transmission?

How to fix my transmission when it only shifts to park and neutral in a 2004 Ford Explorer? The car turns on and everything else works fine. it will go into park and stay and it will go into neutral and stay. It will not go into reverse or drive. If you let the car sit for a while it will go into park, reverse, drive, neutral, and ect. but once you stop the car and try it again it will not do it.