It seems that your photos have been deleted by mistake. Checking Recycle Bin is a good way. If there are no items in the Bin, then try to perform a Search for files operation using F3 while you're on the desktop. From its menu, choose to search the whole hard disk. If you remember some of the folders/pictures name, then the search will greatly increase the results of your search.
One more way of dealing with this problem is to use recovery software which is able to search to deeper levels of your hard drive.
Recover My Files is another great solution to your problem. Although the software is not free, it allows you to save a big number of files. From its main interface, choose where your know the pictures were, then let the software do its job. Upon finish, a list with recoverable files will be presented from which you can choose what to restore (hopefully, your pictures will be there.)
