The first thing you should do to any balky radio is get an avionics hex screw driver and loosen the hold in screw. Gently pull the radio out of its rack and then slowly but firmly push it back in and tighten the screw. Re-racking radios will often fix a poor contact on one of the connectors at the back of the radio rack.
However personally I think a failed ADF is God's way of telling you to get a GPS
