External Hard Drive not Showing Content in Folders

Please help!!! I had to take my Mac Book Pro in, as it had a hard drive failure for the second time in a year. I have an external hard drive with all my pictures backed up to it. It was working fine the last time I used it, and I rarely use it as I just back up pics when needed. When I plugged it into the updated Mac Book the folders show up but all the content is missing. It shows there are 100,000 files on the hard drive. I have to get these recovered, they are irreplaceable.

The new Mac Book was loaded with Yosemite, which is not what I was running previously.