A solenoid is a long coil of wire with an armature through the middle - usually spring loaded.
If the solenoild is burnt out it means that the wire coil is broken and the solenoid needs to be replaced. It is really not practical to fix the solenoid - you would have to strip off the old wire and rewind it with new wire.
You do not mention the make or model of your car.
Peccavi
May 2009