Reinstalling Tiki may be required because:

you want to switch databases (without overwriting the existing one)
to re-run an installer to fix database problems which may have occured
to retry an installation that got bungled somehow.

To re-install tiki, point your browser to tiki-install.php and follow the instructions. Typically, you need to delete the file named db/lock to make the installer accessible once again.

If it is possible that tiki files on the server got corrupted, you may want to upload and overwrite your whole file structure with the same version. (Or you can upgrade )

You can check for file corruption in Security Admin

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