Ron Thompson

I recently acquired a 1992 Mercedes Benz 300 CE from an insurance auto auction. I have been driving the car for almost a month. 2 days ago the car all of a sudden started acting up and not engaging in to gear and only going in drive no matter what gear I tried putting it in. The mileage is extremely high on the car, and I'm wondering if a bad or extremely old filter was cause my vehicle to operate in such a way. I can't start my car in park now, and can only start it in neutral. But once the car turns over in neutral, it thinks it's in drive and wants to take off. The problem with mot starting in park sometimes I first noticed about a week ago. The reverse not being an option just happened a few days ago when I last drove the vehicle and parked it. My transmission fluid looks like motor oil and the filter looks new on the outside(the housing) but the inside where the filter is actually located looks like sh*t. Excuse my language. I'm stressing out and I hope it's only the filter or something minor, but I'm usually not that fortunate. Funds are low for me, so I have my fingers crossed. I appreciate anyone who took the time to reply with any advice/help. Thank you!!!