Your automatic garage door opener may run for years without any problems, and then suddenly stop operating one day without any type of warning. The door may not open or it may not close properly or at all. It's often good to leave very involved repairs to a professional as these doors are very heavy and the springs that operate them can be dangerous, and of course you should never try to repair electrical devices yourself if you don't know how to do that safely. Before you do call a repairperson, however, you might want to try a few troubleshooting tips to see if you can fix the problem yourself, or know what repairs might be needed.
Remote works but switch doesn't
If the remote for your garage door works but the wall switch doesn't, chances are this is the switch itself and not the garage door. Turn off the circuit for the wall switch and unscrew the switch plate from the wall. There should be two wires inside the switch; disconnect them from the screw holding them in place. Switch the circuit back on and then, holding only the insulated parts of the wires and not the bare ends, touch the two wires together. If the garage door opens, you need a new switch. If the door still doesn't work, you may need to have the wiring between the switch and the door replaced.
Switch works but remote doesn't
If you've replaced the batteries in your remote and know that there is nothing blocking its beam or the receiver on the garage door motor, you probably need a new receiver. A receiver is a small piece that receives that signal from the remote, telling the garage door motor to run. Typically the receiver is detached from the motor itself and plugged into an outlet, with wires running to the motor. You can purchase a new receiver for your brand of garage door motor and install it yourself; just plug in the wires to the new receiver in the same location as the wires of the current receiver and it should then communicate with your remote.
Door goes down then up
When your garage door goes down then up, this often means that two eye sensors are not aligned. These are sensors inside the track of the garage door that send a beam between them, telling the garage door that there are no obstructions in its way. If each eye cannot read that beam, the garage door motor thinks something is in its way and it will not close. Have a repairperson align the eyes properly in this case.