I schedule a payment run of some invoices through the Payment Manager. However just before the check print, i terminated the payment. When i went back to the invoice inquiry screen, as well as the invoice payment screen, the invoices for which the payments were terminated before check printing were not available for invoice cancellation even though the payment got terminated. The option to cancel an invoice was no longer available. I also voided a payment, but could not get the invoice released for cancellation. Is it possible for a terminated or voided invoice payment to be cancelled, and if so, how can this be achieved. Thanks.

You can cancel the invoice for which the payment is voided. (The term "cancel" is used for the invoice and "void" is used for the payment).
If the invoice is already accounted, for some reason Oracle requires you to create the accounting first for the voided payment before you could cancel the invoice. Try creating accounting for the voided payment first.
Also see if your invoice has any holds.