If its plastic, its junk anyway, just drill it out. If its metal, inject some WD-40 into the lock, odds are it probably rusted.
Oh yes, is it cold outside, like down well below freezing? If it is, heat your key (if its metal) with a lighter for about 30 seconds then stick it in the lock and let it sit. Sometimes ice will bind the tumblers up, a hot key will warm them and melt the ice.
'92 Dodge W250 "Dually" Power Wagon
'74 KIT 1106 Kamper Slide-in Truck Camper
'06 Heartland Bighorn 3400RL Fifth wheel
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