Here are some things you can try:

1. Check the thermostat: Make sure the thermostat is set to "heat" and the temperature is set higher than the current room temperature. If the thermostat is not working properly, it could be causing the furnace to malfunction.

2. Check the air filter: A dirty air filter can cause your furnace to work harder than it should and can even cause it to shut down. Make sure the air filter is clean and replace it if necessary.

3. Check the power source: Ensure the furnace is plugged in and that the circuit breaker has not tripped. If the circuit breaker has tripped, reset it and try turning the furnace back on.

4. Check the pilot light: If your furnace has a pilot light, check to see if it's lit. If it's not, you may need to relight it. Follow the manufacturer's instructions carefully and use caution when working with gas and flames.

5. Check for blocked vents: Make sure all vents and registers in your home are open and unobstructed. Blocked vents can cause your furnace to shut down or work less efficiently.

If none of these steps resolve the issue, it's best to contact a professional technician to diagnose and repair the problem. Furnaces can be complex systems, and attempting repairs without proper knowledge or training can be dangerous and cause further damage to the unit.