Thank you Jeff Moden for your reply.
I have compared the indexes on the database(which was restored by using a backup before the modifications).
The index structures are same on both the databases. When I observe the execution plan I could see Index scans which were due to the absence of seek predicates.
We are using a SQL 2012 server. Any tips would be helpful. Same structure on one database is using Index seeks and on the other Index scans.
Thanks,
Raghu