SQLBoar (7/9/2012)
The question doesn't actually imply that the database has ever had any kind of successful backup. So unless you've checked and can rely on already existing full backup - "just do a differential" would probably also fail.
If the database had never had a full backups, then there could never have been working log backups and the log would not grow if the (non-existent) log backups failed for a period of time.
Gail Shaw
Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability