When the database is OK, but some SMF files are damaged, it may be a good idea to reinstall the current version of SMF. This recreates what is called a "clean SMF installation". This might be necessary if

• a mod fails to completely install or uninstall, leaving the forum unworkable
• SMF update/patch fails because of the changes mods have made.

These are instructions to restore the current version of SMF, without making any changes to the database. Then, it will be possible to re-install mods or upgrade to a newer version of SMF. These instructions will delete all mods and other changes to the SMF-supplied themes, and erase all hand-made customizations from all files. It won't delete any "extra" files or directories you may have added by hand or through mod or theme installations. For other options, please seek help at the 1.1 support board or the 2.0 support board.

First -- Backup everything

Backup your database. Make sure you have backed up all your data!

Backup your custom themes and graphics. Make careful notes about any hand-made customizations you have made to files.

Second

Download the large upgrade package for the exact version of SMF that you're using from the download site. Be sure to select your current version of SMF from the drop-down list next to "Select Version".

Third

Extract the package and delete upgrade.php and all the upgrade-x.x.sql files.

Fourth

Upload the files, EXCEPT UPGRADE.PHP (and the .SQL files), to the forum's directory, overwriting what's there, now. You can either use FTP or, in a pinch, CPanel's File Manager. On your forum, if you've replaced the standard smiley files with your own and/or replaced the standard avatar files, you might want to refrain from uploading the 'Smileys' directory and the 'avatars' directory.

Once done, your forum will be in a virgin state, software-wise. All of your members, posts, etc. will be intact. However, none of your mods will be installed now. They will, fortunately, still be in Package Manager. From there, you can either apply/install them, or delete them, as you desire. Any of your mod's settings that are stored in the database will be retained and still be usable when the mod is reinstalled.

If you are using SMF 2.0 and had mods installed you may want to use Fix_Packages.php to remove the hooks that the mods installed. This is a good idea if you see some mods are still installed when browsing the admin panel after uploading clean files.

Remember -- for the best-performing and most secure forum, you should plan to patch or upgrade to then most recent version of SMF as soon as possible.