I need a new thermostat for a Montgomery Ward SFB50145B wall furnace but I do not know what model or brand to get. Carlos R.

Look for any HVAC supply house around your area, they should have it

Um, this is the sewing machine category!

Um, you might try the chainsaw category.

Why is this in the sewing machine category?

Measure the opening, why because the opening is not standard.

I can't speak to the specific model but with most pilot lights, there is a switch setting or button for lighting. If you release that switch or button too soon, the pilot will not remain light. Hold the switch or button ON while you light the pilot. Keep holding the switch or button for about a minute until the heat sensor is sufficiently warmed that the pilot light stays on. Good luck.

There is not much out there at all.
Try http://www.borel-furnaces.com/ they may be able to help.
Hope this helps.

Hardware store, or home center.

if the pilot light stays lit, but the burners don't kick on, it's a problem with the thermostat or thermostat wiring, or a problem with the valve inside the gas actuator