Q: Transmission wont engage Drive or 3rd Gear

Hello, thanks for writing in. Of course, the timing of the transmission breakdown you experienced and the impact you are describing is too coincidental to be unrelated. You have not described any damage to the transmission oil pan, which would have been my first thought as the pan is closest to the ground and if it were hit (dented) such could affect the internal valve body assembly or linkages. The external shift linkage(s) should be checked for damage. The shift linkage controls the manual valve in the transmission which valve has to be in the right position(s), depending on your gear selection, for the transmission to actually work.

With regard to the debris in the pan, if it is a sizable chunk of solid metal. Obviously that could be an important clue (be sure to save if it is to show the mechanic). A mechanic would first look at the obvious and relatively simple causes for the shift faults that you are describing, and the components that would control wiring to the transmission and the valve body itself. If you would like to have the shifting problem inspected, consider YourMechanic, as a certified technician will be able to come to your home or office to diagnose the issue and advise on the proper repair.