If you like your database to be reinstalled, drop all the tables in it. On next page reload it will be reinstalled.
If you want to go through install wizard again, delete app/etc/local.xml file and reload any magento page, it will be redirected to /install.
Going through install wizard will not reinstall the database files.
More Reference :
http://www.magentocommerce.com/boards/viewthread/901/