I can open it on my surface. Should I open it in Anaconda/Jupyter lab or elsewhere? Bizarre this has happened only to one of my notebooks, right?
All of my notebooks have been opened started and saved as notebookX.ipynb. This one had previously opened properly.
Whoa - i just right clicked it from the tree, renamed it. added the “i” and that worked.
So bizarre.! Thanks for walk me through this!!!