2Checkout.coms lost check policy provides you with two options:

1) Stop payments can be done upon your authorization. This will immediately void and invalidate the original check payment issued. The fee for this service is $30.00 USD. Funds will be immediately credited to the account balance and will be reissued as part of your next payment.

2) Check payments not received after 60 days from issue date can be voided per your request, at no additional fee. If the check has been cashed then the check can not be voided and a 2Checkout.com representative will contact you with the appropriate bank documents that will need to be completed. If the check has not been cashed the funds can be credited back to the account balance and reissued as part of your next payment.