My 93' 300SE (85,000 miles) has "decided" it will not go in reverse.

You can put the shifter into reverse but the wheels won't turn in that direction!
Last night I got stuck several times in one of our wonderful mid-west snow storms, the traction control light came on, and it felt like it was restricting my gas pedal, no biggie. Got in the car this AM, and no reverse, can anyone tell me where to start checking for the solution to this problem?
Q/2: I am on eBay watching an 1984 500SL from LA, seller is called "Frontline Leasing" anyone know this guy?