Photos on external drive are gone

Hello,
I am desperately seeking help! I am a Windows XP user and had stored all of my digital photos on an external hard drive (maxtor 300GB). Last week I went to open one of my photo files and it came up "no file found." I had thousands of pictures on this drive and all the files came up the same way. I've tried disconnecting my external drive, running virus scans on my computer and then on the external drive to clean up any problems. It still is showing "no file found." Nothing else on the external drive seems to be missing, just the photos. I am by no stretch of the word a "computer person" so I am at a total loss on what to do. Please Help!!

Thanks in advance for any advice you can offer.