Found it - the Options button is on the File | Open dialog. Checked the "Parse and load entire notebook into memory upon opening" dialog. However, the file appears to be complete gibberish. The same result with the backup file made to a different drive. There was no indication of problems with the notebook when saved.

Are there any possible ways to recover a corrupt notebook?

I also had a crash, spent a bunch of time looking for the " Notebook Options" dialog. Couldn't find it. Went to the Wolfram community. Read down two pages just to find how to search. Oh, that's where it is. So now I can pull up the file.. The error stuff tells me there is an error in a certain numbered line. Pull the file up in the form that lets me look at it ... in a form that has no line numbers. Besides which no human other than a full-time Wolfram guru has a chance of fixing the problem ...

So ...?