No start database manager command was issued. SQLSTATE=57019

I had a look into db2diag.log file and I got a unusual hack from one of the website

I followed the steps mentioned below and it worked

a)   db2trc on -f db2trace.out
b)   db2start
c)   db2trc off

This looks like something is wrong with the installation. There should be some hints on what DB2 ran into in the db2diag.log file (look under ~/sqllib/db2dump/db2diag.log).

What you could do if the db2diag.log does not provide a clue is to verify your installation is correct. DB2 includes a tool for that named "db2val". Here is the link to the documentation of db2val for version 9.7. Just run "db2val" as the instance owner and check the output.

This problem generally occurs if you have recently changed the password of the account which is the owner of that db2 instance what you need to do is go to services-> properties of the db2 instance -> and then from log on part select local system account