The first thing you need to do is to reset the sensors which control the operations of a garage door opener. Disconnect the garage door opener from the power source and wait for approximately one minute. When you plug back the door openers back, the sensors will automatically reset themselves.
Battery in the remote of your garage door opener may be causing the problem. Normally, a 9-volt battery is used to power the remote. From the instructions manual that came along with the garage door remote or from its back, read which battery it operates on. Purchase the appropriate battery from a local store and replace the old remote battery with the new one. Make sure you insert the new battery properly, with the negative terminal of the battery in contact with the negative terminal of the remote and positive terminal of the battery in contact with the positive terminal of the remote.
After you have replaced the battery in the remote, you need to reprogram it. Depending on the type of switch your garage door remote uses, you need to verify a few things. If your remote uses a binary rocker switch, ensure that one side of the switch is set to ‘Open’ or ‘Off’ while the other side is set to ‘Closed’ or ‘On’. If that is not the case, configure the binary rocker switch accordingly. For a trinary switch, ‘+’ on the top, ‘0’ in the middle and finally ‘-‘ on the bottom are the right settings. If the settings are different, make the necessary changes.
On the motor head of the garage opener, press and hold the ‘Learn’ button. While still holding down the press button, press the same button on your remote control. This will reprogram the remote in such a way that the remote can control rest of the mechanism.