Hey there, older versions of the Stacks wallet pre-Stacks 2.0 will not work for transacting, but your Stacks remain accessible via your Secret Key which is either a 24 word phrase or a hardware wallet such as a Ledger or Trezor.
The Hiro wallet “accepts” 12 word phrases but generates new addresses in the process that do not correspond to STX balances or addresses from the initial token distributions. If there’s even a slight chance that you may have used a hardware wallet it would be worth checking that, or you’ll be looking for a 24 word secret key.