Hello, we are experiencing unusually cold weather, the garage door opener started making a really loud noise, and the opener will not open the door. Please help if you can.

Door frozen to the ground. If it is a wood door it could be water soaked and too heavy. As temps change the doors will tend to move around some. Inspect the spring to be sure it is still working properly. They tend to break e very couple of years.
DO NOT attempt to fix it yourself. The springs can be very dangerous and best left to a professional.