Payroll - Forgot to post last pay period and started a new year.....now T4`s aren`t correct along with Jan remittance

I issued payroll cheques and forgot to post with the anticipation of starting the new year. I did print employee paystubs and now their YTD T4 amounts aren`t calculating correctly as I missed posting the very last pay period. How can I correct these amounts to reflect correctly on the T4`s and make my adjustment to my remittance amount for January...help please.