Late one night the keg was hooked up the wrong way and I got here in the regulator now the high pressure gauge doesn't work and you cannot move the adjustment knob.
A regulator is a piece of finely adjusted equipment and if faulty would need to be serviced by an expert in the field. With the high cost of labour today it would be more financially expedient to go out and buy a new one. Given the large ammount of energy contained in a CO2 cylinder akin to a loaded firearm I definitely would be chucking the faulty one and replacing it.
I had this happen to me last week. My first brew kegged. I overfilled the keg, connected to wrong valve.... was a bit worries, but no probs. All working.