Diagnose first. If 1996 to present, an OBDII scan might help point you in right direction, if the ECU has detected a fault, for example a shift solenoid.. Could be anything as easy as adjusting linkage, to a solenoid, to as serious a needing a complete re-build
the sunshell gear is stripped out
There is also a small switch on the transmission that goes bad.This prevents the transmission from shifting. Bring it to a transmission shop and have it changed. It usually costs about $100 or so including labor... or you can do it yourself.
bad transmission
A seized up transmission can cause a Volkswagen Golf with an automatic transmission to not shift and racing RMPs after second. A worn gear can also prevent shifting.
If your car won't shift into reverse, try changing the transmission fluid and filter. Sometimes that will solve the problem. If that doesn't help, there could be a problem with the linkage or the shifter cable. Or, if the car is an automatic, make sure you're stepping on the brake pedal before you try to shift out of park. You may need to have a mechanic inspect the transmission.
need more info.year,model.
Sounds like the magnets!
Low on fluid. Linkage mis adjusted or broken. Internal parts malfunctioning.
Bad transmission? Bent shift linkage?
try changing the filter and the trans fluid
If the automatic transmission on a 2002 Kia Rio won't go into park and there is no reverse, there is a problem inside the transmission with the gear bands. Each gear has a separate band and sometimes they wear out. New bands need to be put in or a new transmission needs to be installed.
try the shift sensor on the side of tranny