What program are you trying to view them in? Are you double-clicking on them and "Windows Picture and Fax Viewer" comes up? If that's the case, try opening them in an image-editing program like MSPaint (included with Windows) or GIMP (freeware). If these programs can't open them, then, chances are, your file(s) is corrupt.
Agreed , and if U still wanna try to open them try this:
Open any folder.
Go to Tools>Folder options
Uncheck the Hide extension for known files and click ok
Go to your pictures . Right click one and change it's extension. (to bmp or gif)
photo.jpeg to photo.bmp
Try opening it.
Go back to Tools>Folder options
Check the Hide extension for known files and click ok
Changing the file extension may make problems even worse. This is because the file extension doesn't matter. In a way, you could open a WAV file in an image-editing program and it appears like a perfectly normal image. It's the file header data that matters. If you open the file in a hex editor, BMP files will always start with "BM". I write programs that deal with BMP files so I know BMP's file header data very well. I could study the file format for JPG to see if something is amiss, but I'll need to see it in a hex editor.