I need help plzzz....shift solenoid code...???

hello...i have a 01 galant gtz ( automatic ) and i was just crusin around and suddenly chekc engine came out and car didnt wanted to drive...now i cant even move my car....i put on all gears and the car sits still ( car starts and everythin is normal )....i checked the check engine light and it says SHIFT SOLENOID "D" ..... i hope its not a big problem .....can u guyz help me with it....where is it located or wat should i buy.....