External Hard Drive Trouble

First off, I apologize if this is not in the right section. But my problem is with my brothers external hard drive it had a video folder on it to be viewed through ps3. I plugged it into my moms laptop and copied a music folder over to the external hard drive named "Adams music." A few days later he went to use it via ps3 and didn't show any videos. Plug it back into my moms laptop and the video folder is there but was now a 32kb file. I figured if we deleted that file that the space that was being taken up on the external hard drive would be removed but that wasn't the case. So when I went to put the 32kb file back on the external hard drive the laptop said the file was already on the hard drive but now its not visible since i deleted it. So i was going to just reformat it and start over but I wanted to make sure there wasn't a way to fix and recover the videos (that are still taking up space but not visible.)

Thanks for any help