Sounds like the springs to assit the door lifting have broken.

I agree with joed thatit sounds like a door spring is broken. Check forst and see if that's your problem.

If not post back and we'll try something else.

I would check the wheels and mounts that ride in the two side tracks. If it is a broken spring it would seem to me you could still open the door with extra force.

Thank you for all your response. Yes, I noticed that one section of the spring horizontal across the door had broken, I heard that it is a torsion spring. Is it easy to find a replacement for this? And is it a DIY job to replace it? Thanks.

This is not a DIY job. Call a door specialist. They will probably replace both springs.

once more I'll second joed that this is not an easy DIY job and is best left to a garage door repair company. Best practice says that the springs should be replaced together so it's quite appropriate to replace both and not just the broken one.

It's not really an unusual repair and replacements should be quite readily available.

Thanks. I took your advice and got it done by a door repair specialist. There are many of these repair companies around, and surprisingly the quoted prices range from $175 to $399. As I was still calling and comparing price, one guy who I call earlier drove his van to my garage and offered to do the job at $250. I said I had a quote for $175, he knocked it down to $200. He got the job and finish it in 30 minutes. I am very pleased with the job he had done, and he warranty his repair job for one full year. I just want people to know that, like many other services, it really pays to shop around, there are tons of competitions out there.