2
hmmmm
if you're not bothered about saving all your posts and content, then just drop all the tables using phpmyadmin and then go thru the install process again.
what reason did u have for reinstalling? as if it was just user problems that messed the site up etc, then it shud be possible to just copy all the XOOPS files except mainfile.php and it shud then work.. so u cud just re-enter the MySQL info back into mainfile.php.. ie db host, db user and db password..