WSS Search Service failed to start

You try to start WSS Search engine but received an unknown error. Unknown error cannot give you any clue what was wrong with the Search engine. Fortunately, you can check the error message from Window's Event Log.
1) At the Control Panel, select Administrative Tools --> Event Viewer.
2) Select Application. Double click on the Error that caused by Windows SharePoint Services v3.

If you receive the following error message:
CREATE DATABASE permission denied in database 'master'

Most probably is the User Account that you use to start the Application Pool for Sharepoint site has no permission to create database in SQL Server. WSS is not using the user name that you used to start the WSS Search service to create the database. Therefore, even if you use Administrator account as the Search Service account, you still won't be able to create the Search database.

To solve this problem, you can create the Search Database manually in the SQL Server and then grant necessary permission to the account that you used to start application pool in this databse. After you grant the necessary permission, try to start the Search service again.