2006 Altima won't shift into reverse or park

Is there any warning lights or malfunction besides this?? There are three main parts that may cause this: Park/Neutral safety switch(located on the transmission), Brake pedal switch(located at the brake pedal), Shift lock solenoid(located below the shifter). P/N safety switch prevents the shifter from shifting out of (P) or shifting into (R/P) while vehicle is in motion. Brake pedal switch sends a signal to release the shifter lock to shift out of park. Shift lock, locks the shifter as describe above and is located at the shifter base. I recommend inspection/replacement of the shift lock solenoid and P/N safety switch as its an intermitted problem. Hopefully this helps

Shift locks were added to cars in 1989 when Audi's were reported to be unintentionally accelerating. Since they started coming from the factory with shift locks all cars have some type of bypass so that you can move the car if the battery is dead. In the case of the Nissan Altima you pull the little chrome circular piece out of the shifter console, (Nissan makes this piece come out very easily) and use a key, screwdriver, nail, etc. to SLIGHTLY depress the shift lock mechanism and the car will shift into and out of reverse gear. Check fuse 21 for the Altima as ths is the most common problem.

Faulty shifter assembly, try changing unit (a junked unit in good condition is cheeper)