91 626 problem

My 626 drivers side door cannot be locked because if it is locked it is impossible to open it again i have to take the panel off and do it manually why is this

Electric or manual?There is a small plastic clip that holds the actuator arm to the lock mechanism. It has a habit of breaking with age. If u r locks are power, there is a switch that locks and unlocks the doors and sometimes it goes bad and will have to be replaced. BJ