I know it doesn't help you - but I would ask your host why they only keep one copy of backups - this is next to useless. We go back 2 months with a maximum of 6 hours old for any backup for all our clients/servers.
They are also then taking full backups which maybe is where the issue lies as the MySQL tables are probably not backed up properly and so corruption may have occurred.
Incremental backups of the sever are far less intrusive.
Just a few thoughts - although they do not help your current situation.
