Chandu and Bapi, now that you fellas have the transaction log shrunk, you may want to start asking yourselves some more questions...

• Why was the log file so big in the first place?
• Do I have the correct recovery model? (Full, bulk-logged, simple)
• Are transaction log backups being taken?... how often?...

Books online should be a great resource for you on disaster recovery and transaction log management if you don't have much experience in these areas.