From reading around, people have been keeping IronHax 2.1 save file and installing IronHax 2.5 to another save slot rather than overwriting the IronHax 2.1 file. You should probably have done that

Unfortunately not much you can do with it anymore :/ unless you know someone who has Cubic Ninja or OoT that could reinstall your IronHax. Or maybe a trusted member here you could mail your 3DS to so they'd re-install IronHax.
Probably worth it IMO, because that way you'll always have a backup method available if you accidentally messed up something, or if someone else accessed your 3DS and messed up something in your place.
Please never get IronFall 1.2, it patches the exploit used for IronHax.
I think SmashHax only works for N3DS so you may be out of luck here (I think I understood that you were on O3DS yeah? Or at least you say you were picking the OLD 3DS option in IronHax installer, so correct me if I'm wrong.)