Broken door knob, cannot enter room
I know I don't need to mention that knobs with an emergency release
inside the house are wonderful things. Many function by sliding a nail
into a hole in the middle of the door knob, others use the push/turn
technique.
First thing to try is pushing the door knob in and then pulling it out while turning it as far as you can in both directions. If a part is worn out or misaligned, sometimes this is just enough to do the trick. If that doesn't work:
Now that the pins are out of the hinges, try working with another person if you can. Don't concentrate all of your efforts on the latch if you haven't been able to access it because of the moldings. Hinges get sticky and may need a good nudge.
Have one person push the door up from the bottom or top with a small pry bar or large screw driver. While this is happening, watch the hinges. They fit together like a jig saw puzzle, there should be play and they will loosen up a bit now. Now you will have an idea of the best way to try this.
Remember, the hinge side is no longer attached, so caution is in order. If you are working from a side without molding, pull out from the bottom and/or top while lifting gently with the pry bar. You can sometimes use a fulcrum and step on the pry bar if you are alone.
If molding is blocking your side, try pushing the hinge side inward. If that doesn't work, Using the pry bar, go to the bottom corner on the door knob side and tilt the door toward the opposite corner as much as possible.
If you can, jam something as sturdy as possible (screwdrivers)above and below where the latch is. With another screwdriver of tool, push directly into the latch and push the handle of what you are using in the direction opposite the door. Give it a good yank.
Try to be observant and creative while doing this. You are looking to try and squeeze out just a little more space. Use any area where you see play. Underneath, along side, up top, where ever.
There will undoubted be some damage to the wood or paint, remove the molding piece alongside the latch. It will be affordable to replace if you are a diy person.
For the others that commented, parts inside get worn and as mentioned above, the shaft has to be aligned correctly. If not, you run into problems like the latch not fully engaging.
Cutting the knob off will be a bit difficult. Even when that is done, it may be difficult to remove the latch and metal burrs are razor sharp. I think I would call a handyman before attempting that. Good luck all.