she drives forward fine…no reverse any option to a tranny rebuild? An electrical switch or some additive that might work??
Have you checked the level of the transmission fluid?
If not, that is the first thing that I would do if I was in your situation.
If the fluid level is normal, then there is the very real possibility of internal transmission problems. However, nobody can accurately diagnose this from afar. You need to take the car (or, preferably, have it towed) to a well-reputed transmission shop for diagnosis.
I would strongly advise that you go to an independent trans shop that has been in business for at least 3 years. AVOID chain operations like AAMCO, Lee Myles, Cottman, or Mr Transmission unless you want to be told that you need a rebuilt transmission–even if the problem is a minor one.
Incidentally–just for our edification–how often have you changed this transmission’s fluid?
If the answer is…never…or…I can’t remember when…then a transmission rebuild is a likelihood.
Trans fluid should be changed every 3 years or 30k miles, so this car should have had its fluid changed 7 or 8 times in its life. Have you done that?
Prepare to Benz over…
Check fluid. If level okay I would look into a used transmission myself. They are not that expensive used and this car is relatively simple.
I assume this is an E300? If so, I’d post this on a ‘W124’ forum (that’s the Mercedes internal model number). These are VERY popular, and run forever with ($$) upkeep. Here’s one forum: