can't open .jpg files

Suddenly, all the .jpg files in My Pictures and elsewhere will not open
because the computer cannot find them. I get an error message

"Windows cannot find 'C:\Documents and Settings\my name\My Documents\My
Pictures\file name.jpg. Make sure you typed the name correctly and then try
again. To search for a file, click on the Start button, and then click
Search."

Now, when I click on the Start button and then click Search and search for
..jpg - I find 784 files. But of course I can't open any of them.

Help

Ron