hi, Brett !

What I ended up doing was opening the file with the Open the 'Open & Repair' Option
found by clicking on the 'Arrow' next to the Open Button in the Open Dialog Box.

if even doing so, can't put back data validation' drop down buttons on that sheet
AFAIK, when a sheet has corrupted that much, there is no human power to restore it, so...

[maybe] you will need to re-create 'the worksheet' [and delete corrupted one]

if any doubt [or further information]... would you please comment ?
regards,
hector.