Why can't you lift it manually? Is it because it's too heavy or is there interference from the opener? A properly operating and balanced door should open easily manually without a lot of effort.

Release the opener with the door all the way down and then press the button. Does the trolley go all the way back like it should? This indicates that the opener is working OK but there's a problem with the door.

It sounds like you probably have a broken spring on the door. There are two basic spring configurations. One has two long springs at the roof that run parallel to the tracks one on each side of the door. The other has a single torsion spring located above the head of the garage door.

Hope this helps.

If you can't manually lift the door then there is a problem with the door not the opener. Check the springs and see if one of them is broken. Check the wheels and see if they have broken or come off the track.
Do not attempt to repair the springs yourself. Have the door serviced.

if you have the two tension springs (parallel to the tracks there is no reason why you couldn't repair them yourself. torsion springs on the other hand are most often best left to the professionals.

I have a similar problem but the problem is with the trolley. The trolley does not go all the way back up to the motor. This is as a result of some chuckle-head turning the handle on outside of the garage door, thus locking the door, and then pressing the door opener button.

How do I reset the trolley?