This worked for us...
1 From the Start menu, choose "Run." and type in "Svrmgrl".
2. You should see the following screen, which tells you which version of
Oracle is in use.
3. Type in "connect internal" to start the local connection.
4. Type "startup", at which point the database will be mounted.
5. Type in "exit" to leave the Oracle console.
Pre-requisites:
TNS Listener service must already be online.
User is part of the Oradba group.