obviously the first thing should be to backup the log, but what is the point when the database is offline and you will get an error?
BACKUP LOG [QODTest] TO DISK = 'c:\QODTest_20140718.trn' WITH CONTINUE_AFTER_ERROR
Msg 942, Level 14, State 3, Line 2
Database 'QODTest' cannot be opened because it is offline.
Msg 3013, Level 16, State 1, Line 2
BACKUP LOG is terminating abnormally.
But if the database is in the OFFLINE or EMERGENCY state, BACKUP is not allowed even with NO_TRUNCATE.
Best practice is to backup the log, but in this case the first thing you should do (imho) is to restore the last full backup (WITH REPLACE), otherwise you're wasting your time executing something that will fail.