I have an older furnace that seems to work fine. However, periodically it will stop working. Even though the thermostat has a call for heat, the furnace will not turn on. Then all I need to do is flip off the power for 10 seconds and it seems to reset it. As soon as I do that, it fires right up. How do I fix this? I have had 2 contractors come in and just try to sell me a new furnce. I will replace it next year, but want to see if I can fix it for the time-being

If you have a flame sensor clean it with fine sand paper or steel wool.

I had the same problem and replacing the Inducer Motor Assembly (about $120) took care of that. Mine is a Goodman GMS8 series. Part under warranty for 5 yrs. Heat exchange for 20 yrs. My Motor was squeeling loud. Also check the pressure switch (about $35).

If you are talking about turning the toggle switch off at the furnace and turning back on when it starts working again maybe check the toggle switch.