UPDATE:
I was able to recover the pictures. Thanks for all the suggestions.
Card was not locked.
Menu options weren't changed (aside from which I know the pics saved to the card b/c I'd gone back and reviewed them at multiple times throughout the day).
My brother tried multiple recovery programs and had success with ZAR v. 9.2 (they have newer versions...this is just the one he happened to have from a recovery attempt on his phone a year or so ago). ZAR is the only one that was able to search deeper into the memory card and found all the pics.
Interestingly enough, there were 172 pics that were lost and when he checked them all for recovery and began the process, a progress bar showed on the screen. The first 171 pictures took just a few minutes and only about 1/3 of the progress bar. When it got to picture 172, it took another 10-15 minutes and the remaining 2/3 of the progress bar. Things that make you go hmmm...right?
So, after having them all saved to a folder on his desktop he went to transfer them to a flash drive for me to move them over to my computer and when it got to picture 172, the flash drive balked and said "no room..." This prompted him to investigate further and he discovered that that 172nd picture was 8 GIGS which explains why that last picture took so long during the recovery process! Don't know if that weirdness happened when the recovery was being done or if the memory card is the one that did that and which caused this whole mess in the first place.
Either way, I can't trust the card anymore and now don't trust the brand either. Without knowing what caused the problem in the first place, I'm going back to Transcend and hoping that sticking with a more well known brand will prevent this from happening again.
