Q: I lost my files in my external hard drive

I plugged my external hard drive to my smart TV and the next time I plugged it to my macbook, I lost a whole folder (i.e. movies). However, it still occupies the same memory space so I don't think they're deleted. They're not hidden either, as I have set my hidden files as viewable. I also recently updated my OS to yosemite. I don't know how to recover my files. I keep finding steps on how to recover lost files but they're all for Windows. Help?