This is known as limp-in mode. An error has been detected by the transmission control system and you need to enter the self diagnostics to retrieve the trouble codes. Only specific diagnotic tools can be used for code retrieval.
Transaxle controller monitors transaxle for electrical or internal problems. If battery voltage is lost, or transaxle controller senses a transaxle failure and fault code is set, transaxle enters and stays in limp-in mode until failure is repaired. In limp-in mode, only Park, Neutral, Reverse and 2nd gears function. Transaxle will not upshift or downshift. Vehicle can be operated, but performance will be reduced.
NOTE: Transaxle will not enter limp-in mode when certain fault codes are set.