Sears Electric forced air furnace stays at 60deg

[Justin Case]

On of my unit's Sears forced air furnace is blowing room temp air. It is about 7years old. I don't have model number at this time. I had tenants turn it off for awhile and back on.

I know nothing about furnaces (yet).

Any suggestions on how to troubleshoot before I call handyman?

Can anyone post pictures of thermostat so I know what to look for? How to reset?

Could a dirty filter cause this?

Thanks,