iammrsspeed

My 2009 GL550 won't shift from park into neutral, drive or reverse. This has happened before, but after tapping the gear selector level located on the right side of the steering wheela few times or shutting off the truck and restarting, it would eventually shift into drive. Now...nothing. I tap the button on the end of the shift wand and don't hear a click or shift sound at all. Is there anyone that can offer me some advice on what this could be, what it will require to repair, etc? Thanks so very much.