SQL database is crashed

[morrisonn]

Hello,

 Our server was hit by some unknown virus which seems to have corrupted header information for many of our files including an important databases and some of its backups.  However the log file (.LDF) for the live DB was not affected. We also have a relatively old .BAK backup file. 

Is it possible to bring the DB (.MDF) in the old backup to Live standard using the new/latest Log file? If so, how? Any help is truly appreciated.

[RuneLassen]

Follow the steps mentioned below:

* Take a tail log backup of your database after your full backup
* Restore your Full backup available with you using WITH NORECOVERY option.
* Restore Differential backups ( if you have in order) WITH NORECOVERY option
* Restore Transactional log backup in order WITH NORECOVERY and the last tail backup taken using WITH RECOVERY option..
Also have a look this Recommended actions

https://community.office365.com/en-us/f/172/t/266070

[morrisonn]

But how do I "Take a tail log backup of your database after your full backup", since I don't have access to the original DB anymore.

[RuneLassen · Accepted solution]

Ok, If your database is not functional now, then you can't take tail log backup.
In that case, try the steps given below:

* Detach your database
* Copy your LDF File to a new location
* Attach MDF File without providing LDF file..

Test whether this works or not. If not then can try the tool SQL Server Recovery Toolbox. It is possible you will be able to help. http://www.oemailrecovery.com/sql_recovery.html

[morrisonn]

You've been very kind in your efforts to help. Thanks for that. Solved!