Reconnected my Passport, now not working! HELP PLEASE :(

Hello there. I bought my MacBook Pro brand new in March of this year. I bought my WD My Passport external hard drive 1 TB in June 2014. I searched online how to reformat it to Mac, and it worked fine. I was able to drag and drop all of my 20,000+ pictures into the hard drive. It seemed everything was fine. I did that in June 2014. Well, tonight I try to reconnect my WD Passport because I have more photos to save onto it, only to discover that my computer will not read it again. It does not show up under Devices. If I go to Disk Utility, the Passport drive shows up, but that’s it. I can’t get into it and “Hilary’s Passport”, the name I gave it before, is not showing up. I’m so scared I’ve lost all of those pictures! 

Please help! thanks

Hello,

Take a look at this link.

How to test a drive for defects or problems on a Mac