Picasa is a free application from Google that allows you to organise, view, manipulate and share all of the photos on your computer from one window. Picasa scans your hard drive automatically for new photos and adds them to the database when it detects changes on your computer. If the database file has become damaged, however, you may find that you are no longer able to see certain pictures or that some photos do not display correctly. Picasa has no built-in function to rebuild or refresh the photo database, but you can force it to do so by uninstalling and reinstalling the program.
Open the Start menu and then click "All Programs."
Open the "Picasa 3" folder and then click the "Uninstall" icon.
Click "Yes." This deletes the existing Picasa database from your computer.
Click "Finish" when the uninstall process is complete.
Open a Web browser and navigate to picasa.google.com. Click the "Download Picasa 3.8" button on the right side of the window and save the file "picasa38-setup.exe" to the desktop. Note that the version number will change as Google releases new versions of Picasa in the future.
Double-click the file "picasa38-setup.exe" when the download is complete.
Click the "I Agree" button.
Click the "Install" button.
Click the "Finish" button to launch Picasa and rebuild the database.
Deleting the Picasa database does not delete or modify the images on your computer. However, Google recommends backing your images up for maximum safety before deleting the Picasa database.