Android

Hello everybody!

I got a preordered g1 and have been loving it ever since. I had taken several dozen photos and had them on my sd card.
Recently when i went to take a photo it said sd card error. I took it out and put in back in and the camera worked again but all but 1 of my photos had disappeared. I tried viewing the contents of the sd card on my computer but they were not available there either. Strangely though my background picture is one of the losst photos but it still remains as a background!
What is the likely cause of these lost photos?
Any help with this problem is greatly appreciated

JZ