Oh, so you bought a used guitar... you should have compared it to a new one.
Anyway, which parts do you mean? The bridge, the Pickups, ...?
Hopefully, you will find original replacements easily for most of the guitar parts if you went to a guitar store & checked out Ibanez accessories and replacements.
If you don't know too much about these stuff, take your guitar to a technician , just to make sure the job is well done.