Could you list the job and skill levels for your characters? Characters can be rolled back, but it would have been asked specifically by you (the owner of the account) and it woould need a strong reason (such as someone obtaining your login data, steal all your gear and/or delevel all your jobs to 3, getting you banned for RMT, etc.)

So I suspect you are merely confused and mixed up your main/alt. (Alts usually don't level advanced jobs. Maybe lvl 20 to fish and ride chocobos.)
But you could try asking a GM to check your account for any rollbacks/abnormalities during your absense. Those should be logged.