auto trans stuck in 3rd gear

hello i got a 91 3000gt sl at and my trans is stuck in 3rd gear what do u guys think it is maybe its the computer or the gears cause if its the gears i migh as well selling it rite any way i had this car for 6months and last month i decided not to drive my car for like 2days after 2days i drove it and it wont go in no gears its allways stuck in 3rd gear there is no 4rdgear nothing i think its the computer because if it was the gears the 4rd gear would not go bad rite? please help me i love this car and i dont want to get rid of it i already have 2.5exaust.intake alittle weight reduction and i love it so please help me. thanks

check the fuses for the transmission

check the tranny fluid :P

where are the tranny fuses located

your car is stuck in failsafe mode. When a problem is detected in your transmission, the TCU will throw you in 3rd gear to let you know there is a problem. Your tranny is throwing a code and you need to get access to either a datalogger or something that you can use to pick up the code manually from the diagnostic port . . . either that or you'll need to take it to the stealership or try to find some other shop who can pull the code.

thanks hotshot