Classic/Antique Car Repair: RR Corniche 81 Transmission, transmission fluid, debby

Question
'81 Corniche seldom driven, tonight after jump starting vehicle will not move into gear, any gear, neutral, drive reverse etc., Suggestions on the order in which we could self diagnose and repair the issue?  Vehicle needs to move garages for storage

Answer
Hi Debby:
If the vehicle was prepared for storage at its present location,
all fluids would have been drained (including transmission).

If this was not the case, it depend on how long it has been setting and
what condition the transmission is in. Check the transmission fluid to
make sure there is fluid and the condition of the fluid. Also, if fluid
is present, let the car warm up for 1/2 hour. If after that, there is no
movement in the car, you may have a disconnected shifting linkage, which
will need repair.