I'm sorry to hear that. Do I understand you correctly that it is the screen locks code you can't remember, not the SIM-cards code? If so, I suggest that you perform a software repair using Xperia Companion (clickable link)
A Software repair will remove all stored data on your phones internal memory and the screen lock, and then reinstall the latest available software version.
Since you can't get into your phone you can sadly not perform a back up, so you will unfortunately lose all data that isn't saved on a SD-card or cloud service.