I had a similar situation in a userform, I never did find where or how.
To recover, I had to rebuild the form, or load it from an earlier save
(I also exported the form after I created it, so I could also import it
too.)

If you have not saved a prior version, or have not exported the form,
you are pretty much out of luck. You may get lucky by closing
everything and rebooting the machine, loading the workbook, and then
exporting the modules so you can recover later.