If your door opener is still going up but not going down, then you may have a failed sensor. More likely you have a wire problem connected to the sensor. You might also want to check the alignment of the sensors.
If the door opener isn?t moving either direction, you may have a problem with logic board on the motor unit or a tripped electrical breaker.If you refer to your Owner's Manual there should be additional information on troubleshooting and aligning the sensors, such as the information below.