Your looking at one of two problems.
1. The rollout switch is tirpped and/or bad but, possibly has a manual reset on it. This may be the type with a small red button in the middle and all you have to do it press it back in. The other types requires replacement.
2. You have a stuck relay on the circuit board and possibly a light tap will unstick it.
If that doesn't work then replacement of the relay is in order.
Don't call an HVAC tech as they will not do in-the-field board repairs and will charge you for a replacement board to correct a simple relay problem.