Top best answers to the question «How do you free up a stuck gas valve»
Replace the valve while the gas is off. It is probably a "T" handle valve and if so you just need to use more force to turn it, or slightly loosen the nut on the bottom, turn the handle, and then retighten the nut. BUT, you should replace the valve and to do that YOU will have to turn the gas off at the meter anyway.
Heres how; First, turn off the gas in the house so you don't blow yourself up or cause a disaster, loosen the bottom nut, tap the bottom of the plug upward to loosen the tapered plug, remove the tapered plug, lubricate with a special gas valve grease , and re-install the plug, job done.