Which The Last Stand are you talking about? If it's a local savegame you're referring to (offline, on your computer), trace down the associated cookie, and simply delete it, now start afresh. The savegame is stored in that cookie.
To locate it, see https://en.wikipedia.org/wiki/Flash_cookie#File_locations . These flash cookies/local shared objects get named after the games here, so they're fairly easy to recognize.
Basically, the only option is the one Unleashed presented to you chetanya1... the option Macll suggested only works for smaller Flash Games, the MMO games all use online saving for every account. =)