This sounds to me like it might be a corruption on the SD card that is causing problems. What I would recommend is transferring all the files from the SD card to the computer then using the computer to format the SD card and test it out. I would not put any files back on until you have taken a picture or two to test the SD card in the phone.
If the SD card continues to fail to show you the files, try the SD card in another phone and see what the results are. If it works in another phone, then obviously the issue lies with the phone you received. If the issue FOLLOWS the SD card to the other phone, then you may need to replace your SD card.
Hope all this helps!
Since your pictures are showing up properly that is a good sign. Have you tried going to the Android market and downloading the MyBackup Pro app in your new phone? Once it is downloaded, your should be able to access the files that are on your SD card that pertain to that app.
Thank you Alicia_b! That did it actually. I figured it out last week, but now I can't figure out how to close this lol. I was trying to avoid going that route because it was a paid app but I figured out that I can re-download for free it was just a bit of a convoluted process. I appreciate your help!