In order to void invoices from the prior closed period, you may want to create customer 'credit memo' and then apply credit memo against the outstanding invoice.
Refer to these articles that deal with how to void checks without affecting a prior period
http://www.hhcpa.com/blogs/government/two-helpful-quickbooks-tips-to-protect-prior-period-data/
http://vpcontroller.com/how-do-i-void-an-outstanding-check-from-a-previous-period-and-re-issue-a-rep...
