Sensor fault
The opener will not close if the beam is blocked.

Door movement
When the door opens normally but will not close, the safety system is usually stopping it. Sensors are the most likely cause, but limits, tracks and controls can also be involved.
Short answer
Check that nothing blocks the sensor beam, clean the lenses and confirm both sensor lights are steady. Check the wall control for lock mode. If the door starts closing then stops or reverses, the limit or force settings or a binding track may be the cause.
The opener will not close if the beam is blocked.
The opener misjudges where closed is.
Resistance during closing triggers reversal.
Lock mode or a faulty remote. See sensor repair.
A door stuck open is a security problem, particularly overnight. Many openers will close the door if you press and hold the wall button, which overrides a sensor fault while you watch the door. Use that only to secure the home until the sensors can be repaired, and keep everyone clear while it moves. Note whether the door moves at all when you press the remote, since a door that does not even start points to sensors or lock mode rather than the tracks.
Describe what the door is doing when you call. A provider may ask follow-up questions, but a reliable price normally needs an on-site look rather than a phone-only quote.

Photo-eye sensors sit a few inches above the floor on each side of the door.

Travel limits tell the opener where fully open and fully closed are.

An opener only moves the door; it should never be doing the heavy lifting.
Usually the sensors are blocked or misaligned. Close limit settings, binding hardware and lock mode are other possible causes.
Many openers close if you press and hold the wall button. Watch the door all the way down and arrange repair.
Yes, if sensors fail. Remote closing is disabled when the safety beam is blocked.
It is a security risk. Use the hold-to-close method or the manual release carefully, then book service.
Yes. A bent track or binding roller can cause the opener to stop and reverse.
Often not. Sensors and settings are the usual causes, and they can be repaired.

Call to schedule a technician visit with an independent provider who serves your area.