Hi,
Thank you for posting your query on Symantec community.
Only DB restore won't help but it will bring back group structure & policies however clients will reamin offline.
When the client-server communications break, you can quickly restore communications by replacing the Sylink.xml file on the client computer. You can replace the Sylink.xml file by deploying a communication update package. Use this method for a large number of computers, for the computers that you cannot physically access easily, or the computers that require administrative access.
Refer the below articles:
Restoring client-server communications with Communication Update Package Deployment
http://www.symantec.com/docs/HOWTO81109
How do I replace the client-server communications file on the client computer?
http://www.symantec.com/docs/HOWTO81116