What do you mean "it cracked"? If he has any damaged files, etc, and not much personal data like setups, then just reinstall the LFS from official download, and unlock it with his licensed account.
If somebody else is using his account, change WEB and GAME password (and don't use the same).
If you mean "cracked" like using S2 without license, then reinstall plus here is the official crack:
https://www.lfs.net/shop/licenseselect