1997 Volvo 850 GLT (B5254T), Automatic, 177K miles

This car does not go reverse. Only goes forward. Probably stuck on 3rd gear.

Here is what happened -
This car was driving fine until last evening. could not reverse from shopping complex. sounds like gear is engaging on reverse but does not move. I could push the car front and back only 2 to 3 inches at neutral gear position which feels like car is in park position. A real slow engine rev at reverse suddenly reversed car and locked the wheels. Felt like car went to park position while going back. Forward gear worked (D Position) but felt like it is in 3rd gear. Somehow managed come back home (2 miles) without stopping and changing gear.

I moved the gear 15-20 times but it did not help.
No flashing up arrow.
ATF level is good and color is good. (changed last year)
Reverse light comes up when gear in on reverse.
Can start car on neutral and park position.

Did little bit of reading but it does not sound like PNP switch.

Any hope for this transmission? Cleaning/Changing PNP switch will help?

Thanks in advance.
Mainak

1997 Volvo 850 GLT (B5254T), Automatic, 177K miles