I need to know if there's any way to open these pictures again.?

In the last few days it seems a lot of my jpeg picture files may have been corrupted. When I look at the folder that they're stored in, I can see that there are supposed to be pictures in the folder (it looks like really small thumbnails), but when I open the actual pictures, Windows Picture and Fax Viewer says "No Preview Available." When I try to open them in paint I get an error saying "This is not a valid bitmap file, or its format is not currently supported." I also tried opening it with Quicktime PictureViewer and it says it cant display because "a suitable graphics importer could not be found." Does anyone know how I can open these files?