I had an MRI - says L4-L5- Disc buldge with superimposed central disc protusion. Severe spinal canal stenosis with compression of the thecal sac with bilateral neurofarminal narrowing. A chair broke and I collapsed on back.?

Pinched nerve. Spinal stenosis is one way to say you have a narrowing or "pinching" of your nerve canal, in your case it is severe. The cause of the pinching is at least in part from a disc protruding into the nerve canal (herniated disc) which could potentially have occurred in the injury on the chair. I would not hesitate to be seen, many good treatment options available.
Symptoms? Prior MRI? Just because the MRI picks up an anomaly does NOT mean anything. The 1st question: are you having any symptoms (after the chair collapsed)? 2nd question: was your back ever scanned before the accident? (Comparison of pictures can help). Use HealthTap Prime & upload pictures to get better understanding. Don't rush into surgery: 40% of deceased people had disc protrusions; majority never had symptom.