How to correct having voided the wrong check or to unvoid a check?
When you void a check, it puts a flag in the record that shows it's been voided. It also adds the date voided to the record. These are simply flags that don't really affect the ledger. They just indicate the check has been voided. In addition, the other update that takes place is a reversing journal entry is created. This is the only thing that really affects the ledger.
Therefore, if you no longer want the check to be "voided," you may delete the voiding journal entry. Although the void flag and void date will remain, the check will be in the ledger as a normal check (a credit to cash and a debit the offsetting account) and will be available to reconcile as a normal check. The reversing journal entry is now gone. However this is not the recommended method as it doesn't follow Best Accounting Practices. Keep reading for the recommended method.
If you want 'cleaner' books, you must leave the voiding journal entry and re-create the check by creating a bill and clicking the assign check number. You would have to add a letter to the end of the check number you assign, if you would like to use the same check number that shows on the voided check. However, if the original check was dated in a closed accounting period, you will not be able to backdate this newly assigned check.