Go to Transactions>Bank>Write Checks>List to see list of checks
To check for all Bill Payment including those that are voided:
To check for deleted Bill Payment:
To check if there was a Bill Payment that was originally assigned 456 then was changed:
After doing all the above process there is no Bill Payment matching up then it is safe to assume that this Check Number was never used orprinted. This is possible by manually overriding the Check Number prior to printing the Check and in this case will not be logged under the System Notes.