The Revalue Nominals function found in System, Utilities will only revalue Bank or Petty Cash accounts. If the Nominal account has to be revalued then the workaround would be to flag it as a Bank (or Petty Cash) account for the revaluation and then return it to its original type.
If Bank accounts are not showing in the list, then it could be the case that there was no balance in your current open period (not working period), in which case check the Nominal account transactions and balances for the current open period.
Note: Control accounts can be revalued using the Revalue Debtors/Creditors option and since these cannot be returned to their correct type from within the account record they should not be amended.