Part of the disaster recovery process is to uninstall and reinstall the SharePoint Portal Server software. You must remove SharePoint Portal Server and then reinstall it before the SharePoint data can be restored
To uninstall and reinstall the SharePoint Portal Server software
Use Add/Remove Programs in the Windows Control Panel to uninstall the SharePoint Portal Server software. Restart the server when the uninstall operation completes.
Insert the SharePoint CD and install the SharePoint Portal Server software using the appropriate options for your environment. When the New Workspace Wizard starts, click Cancel.
If applicable, install any SharePoint Portal Server service packs that were applied to the original installation.