Storage Building Entrance

Break the doorknob off, punch out the inside knob and operate the bolt with a screwdriver

Agreed. That would be the least expensive option. Door knobs are cheap compared to replacing a door jamb or replacing a window (if applicable) and no way in hell will you gain access to the overhead doors unless you have superman strength to lift and break the stops without damaging the track.

Put a huge pipewrench on the door knob. It will turn or break.

If it turns then replace it.

If it breaks, break it off and force the latch open and then replace it.

You must replace your door or its changed.

I had a similar problem recently except I could reach both sides of the door, knob just wouldn't turn. Even after removing the knob I could not move the bolt even via its internal mechanism.

I was preparing to use a thin blade on an angle grinder to cut off the bolt at the keeper but on a whim I tried moving the bolt with a screwdeiver between the door and keeper. It moved, bolt removed, lock replaced, problem solved.

Any chance of using a paint scraper to slide the bolt back?

Have you tried penetrating oil like Kroil or PB Blaster?

Is there a lock cylinder in the knob? If so, will the key turn the lock? If not and if the penetrating oil doesn't work, you can drill the lock cylinder out which might allow you to turn the knob.

If none of that works, the other suggestions of using a pipe wrench to break off the knob and then a screwdriver to retract the bolt is probably your last, best option.

PLZ try to remove this paint and to start new paint at every place.

Thanks to all who replied. Tried the pipe wrench suggestion and with a little effort the door popped open. Tried to find out what caused it to jam in the first place but it all looked normal. Didn't close the door until I had changed out the knob set though and now all is wonderful. Thanks to all who offered helpful ideas.