I'm with the rest. Hard to imagine this happening. Are you sure it's not liquid CO2 in there?
To check, take off the gauges, turn it upside down, and gently open the valve a crack into a white towel. If it's beer, the towel will catch it and you can see or smell it.
If it really is beer, all is not lost. You can drain all the pressure and remove the valve and clean it out, then dry it. Or take it to the place that fills them. They could do it.
Regardless, if you got beer into the gauges and/or regulator, you have to clean them and dry them or they won't work.
For the future, it's worthwhile to install one-way check valves.