Make sure you have backed up your wallet.dat file
Open the folder location of the litecoin-qt program. Right-click the qt exe file, in the menu that pops up choose "create a shortcut," after it creates the shortcut, move the shortcut to your desktop.(if you are running the installed version, you will need to go to the program files folder and create a shortcut of the qt.exe in that folder, it will automatically create the shortcut on your desktop)
Right click the newly created shortcut that you placed on the desktop, and choose properties. The properties window will open.
Place your cursor in the field marked "Target" outside of the quoted string ".......litecoin-qt.exe"
add a space and the " -salvagewallet"
should now look like ".......\litecoin-qt.exe" -salvagewallet
Click apply and then OK.
Make sure your litecoin wallet is not currently running, then double click the modified shortcut on the desktop. This will start the wallet with the salvagewallet function.
Edited for proper commands.