My heater stopped working all of a sudden on my 1997 ford explore truck 2 cylinder

see if the blower is getting power , you either have a blend door or a valve that opens in the hose , check selector panel

Do you mean the fan stopped working properly or the heater isn't producing heat, or both? If its the FAN, check the blower motor resistor. Its a common part that goes bad on older Fords, often collecting leaves, and other debris as its exposed to external air flow coming through theintake path, and all too often debris eventually accumulates enough right there to short it. Luckily, its often directly accessible by removing a couple screws on the engine side of the firewall. If that's what it is, be sure to clean out the cavity the resistor lives in as dry debris there has been known to start a fire before the switch stops working or a fuse blows.