Assuming you cancelled the cheque run via the Payables program (rather than using Windows End Task function) all cheques printed by the program (successful or not) will have been assigned a cheque number.

If at any point before the Payables cheque run finished all of its steps the user preformed an End Task on Payables then there is no way of knowing what information (such as cheque numbers) may have been lost.

Most likely if you have cheque records with no cheque number then the later is what occurred.

If the process had been allowed to run its normal course then when it is finsihed printing cheques Payables would ask if the cheques had been printed successfully Yes/No. If you selected yes Payables will post the cheques to the Vendors account. If you selected No then you will be ask if any of the cheques printed successfully. Those that you indcated as having been printed successfully will be posted to the vendors account and the remaining (with cheque numbers assigned) will be flagged as voided. At any point if you try to exit from the cheque printing you will be asked if you want to void all of the cheque printed with the same result as if you had indicated they had not printed successfully.