Engine/Transmission (1994 - 1998) Hot water problems

[Crupper]

Temperature gage has been on 0 all fall, didn't know weather it was the sending unit or the thermostat, Turned up the heat and turned on the heater and no heat, so knew right away it must be the thermostat. Got a new one at NAPA, took the old one out and it was stuck open with a rubber band that is supposed to be on the out side of the stat, how did it get halfway through the wrong way?