Hello Vinay,
The database connection details, along with the connection details to EEM, ITPAM, etc. are all stored in database tables.
If MSSQL was uninstalled, then the connection details are now lost.
I would recommend an uninstall of APM 12.9 (launch the setup.exe again from the original media), and then reinstall of APM 12.9.
Regards, Gale Bacon