A door jammed halfway, with one corner sitting farther out and a roller hanging out of the rail, is off track. Stop using the button, stay out from under it, and leave the fix to a shop.
Look at the tracks. Those steel channels on both sides of the opening are what the rollers ride in. Sometimes a roller pops out. You will see a little wheel hanging in open air next to the track instead of nested inside it. The panel above it twists. The door will not finish the trip.
People keep pressing the remote hoping it will seat itself. That is how you bend the track or tear a hinge. The opener is still pulling. The door is fighting the steel. Something has to give, and it is usually the door hardware, not your patience.
If a roller is hanging outside the rail
That is the classic off track look. One wheel sits in open air. The door lists. The opener may still try. Stop using the button. Do not kick the bottom panel. Do not stand under a hanging door. Do not shove the roller back in with a screwdriver while the opener still has power.
Pull the emergency release cord only if you need to free a car and the door still feels mostly balanced when you try it by hand, slow, standing to the side. If it binds, stops, or tries to twist harder, leave it. Walk through the house door. Park on the street for a day.
If the door is crooked but every roller still looks nested
That is often a cable that stretched, frayed, or jumped a drum. One side hangs lower. The rollers may still sit inside the rails while the whole panel lists. Keep running it and a roller can climb out next. Same rule: stop the opener. Do not climb a ladder to poke a fuzzy cable.
A tired or broken spring can also leave a door heavy and crooked mid travel without a wheel hanging out yet. If you heard a bang earlier, or the door feels like dead steel by hand, treat it as spring work. Do not wind cones yourself.
If it screeched for weeks before it jammed
Dry or cracked rollers screech every open long before one walks out of the rail. A loosened track bracket, a rail flared by a side mirror or bike handle, ice packed in the bottom of the track, or a roller already walking toward the edge can all end here. Noise that got worse every month is a warning, not background.
What it is not
This is different from a door that hangs midway with no roller out. That one may be fighting a cable, spring, ice, or bent track while every wheel still looks nested. Here you can see the wheel outside the steel, or the panel twisted hard enough that the next cycle will put it there.
It is also different from a door that starts closing then climbs back up. That reverse is usually eyes, travel, or force on the way down. An off track jam is a bind. The opener may hum. The door will not finish either direction cleanly.
It is also different from a door that stops a few inches short with daylight under the seal. That one almost finishes the close. An off track jam freezes higher in the opening.
What not to do
Do not climb a ladder under a twisted door. Do not brace a board under a hanging panel and walk away. Do not spray lubricant into a bent track and keep mashing the button. Do not hammer a roller home while the motor still has power. Each wasted cycle can bend the rail, tear a hinge, or drop a panel farther off the rollers.
A shop that does garage doors will put the door back in the tracks, replace the bad rollers, straighten or swap bent track sections, and check why the door went crooked in the first place. Springs and cables get a look too, because an off track door often started as something else.
I am not a contractor. This is just what shows up when a door hangs in the middle of the opening with a wheel sitting outside the rail and people keep hitting the button. Manufacturer trade notes on residential door hardware live in DASMA's publications library. Those sheets are written for dealers and installers.
The U.S. CPSC garage door operator page covers federal entrapment rules for automatic openers. A hanging door is also a crush hazard. Keep kids and pets clear of the opening until a shop has it secured.
If you want someone local to look, get a quote.