Hi Jayachander,
Have a look at these sap notes:
For taking backup: Schedule from DB13 and get the exact command from Logs
1841993 - SYB: How to schedule backups in DBA Cockpit
1887068 - SYB: Using external backup and restore with SAP Sybase ASE
How to restore DB
1611715 - SYB: How to restore a Sybase ASE database server (Windows)
Divyanshu