First of all, you may be stuck with a broken database. You **really** need to sort out backups of any system that means anything at all to you/your business! It may be possible to recover the database though. Take a **copy** of the mdf file and try to attach it to a test machine: CREATE DATABASE [YourBrokenDatabase] ON (NAME = [YourBrokenDatabase], FILENAME = N'c:\\blahblah.mdf') FOR ATTACH_REBUILD_LOG; This will attempt to attach the database and create an empty log file. I suggest you read [Paul Randal's blog], especially the [post on fixing a suspect database]. That gives a step-by-step approach to sorting out the problem you have. ***Then go and make sure your other databases are being backed up, and also that those backups are good (try restoring them to a test machine). Without backups that can be restored, you have no backups!*** :
There are third party recovery tools that might be able to help out if attaching the MDF file does not work. As others have mentioned above, why didn't you have backups. There is a good saying among many DBA's that backups are actually worthless. It is the restores that are priceless. I am sorry @ramesh that you may have learned this valuable lesson the hard way. Best of luck to you with recovering the data.
If there is only one mdf file then you have the option of using sp_attach_single_file_db
http://msdn.microsoft.com/en-us/library/ms174385.aspx. As @WilliamD suggests, work on a copy of the file you have rescued in case what you attempt is unsuccessful, you may need to revert to the rescued copy. Read the link in the other answer too, it will have very useful and relevant information for you.