2003 Buick Regal Shift from Park to Reverse or drive

This could be a couple of things. As it was in an accident it could be a broken trans mount 1 or more. Or morelikely the cable that shifts the transmission has broken and won't move the car out of gear. If the shifter moves especially. The easiest way to check this is have someone turn the key on and depress the brake. Then have the hood open and look on the driver's side. There is a lever that should move forward and backward. When the other person moves the shifter into drive see if hte lever moves or if the cable is moving in it's housing. If all that does work then you may have a transmission problem. Also there is a switch that lets you shift the shifter and that may not be getting electricity letting itwork.