Doors on the 2005 2500 hd chev truck wont unlock or lock

They are very common for the door latch actuator assembly. Usually it starts when one particular door stops locking or unlocking. The lock rod will only partially go up or down, then gradually stop all together. The actuator used to be a separate component, however now it is integrated into the entire latch assembly. It most likely is the problem and will need replacing. If its just an issue that your key fob doesn't work anymore try replacing the battery in the fob. Then hold the lock and unlock buttons for 7 - 10 seconds to re-synchronize the transmitter.