You could start with this
Ensure your MS SQL Server is listening on TCP1433 (Start cmd window on the MS SQL server, and enter the commandCode:
netstat -an | find "1433"
If you get a blank line as a response, your SQL Server is not listening on TCP1433.
Is the SQL browser service running ?
Try connecting to SQL instance with IP address
R u able to login SQL using SQL management studio?
Try restarting epo services
Check SQL permission is set correctly
Also, make sure that your Database server instance are the same between ePO & SQL
skhairuddin, one you can test is, on the EPO server, create a blank text file (right click on anywhere and choose New > Text Document), name it and save it with extension .UDL. For example, dbtest.udl or epo.udl. After saving it, you will see icon changed. Simply double click on it and open the file. There type in your SQL information and verify connectivity as well as credentials. If this does not work, you need to resolve it before connecting ePO to database.