Hope all is well bought a 2002 s500 back in april and started seeing some problems with the gear box . Id have the car in park and will try to switch it down to reverse. It takes a minute but the call will recognize it . Trying to switch it down to drive the car jumps and doesn’t switch into drive and on the cluster is still says its in reverse or park . I have been told it is the gear shift module needing to be replaced. I have a replacement that I am needing virgin and reprogrammed to the car. I have found a company that does sell virgin gearboxes, but I unfortunately don’t have the funds to get that at the moment. Really looking for guidance and help can pay you for your time .

 

You should learn how to use the forums, i.e. search!
This problem is discussed ad nauseam, and you may need to buy theft blocking used components,
First look at the transmission module for leaks and connector problems.

 

My first check would be the plastic bushings on both ends of the metal rod between the shifter and the transmission.
My second check would be to find the TCM (Transmission Control Module) buried in the right front SAM (Signal acquisition Module) (remembering that left/right is always from the viewpoint of the seated operator) pull it out, disconnect it, open the plastic case, and thoroughly clean the board with brake/parts cleaner, and reinstall.
My third check would be to remove and replace every electrical connector on the shifter several times (one is hard to see).

Only then would I get into sending one of the few shops that can actually program the theft-relevant shifter a lot of money, hoping that it works.

You gave the model and year, but you will get better and quicker help if you tell us everything, such the market for which the car was built, whether 4Matic or not, etc.