The search function built into Windows is an excellent way to find a specific file on your computer. You can also use Windows Search to find all of the files of a specific type on your computer using the "kind" search function. Using the "kind" function to search for pictures and setting the scope of your search to encompass all directories will return all of the picture files on your computer as results.
Click your computer's "Start" button.
Type "kind:pictures" and press "Enter" to see more results.
Scroll to the bottom of the search results window and click "Computer" in the "Search again in:" section.