retrieving passcode for device

You don't sorry. If you're talking about the passcode to lock your device, that passcode is stored inside your device and nobody can retrieve it.

Keeping in mind that if you don't have a backup all data will be lost on your device (except those that you eventually synced to iCloud), pay attention to the specific gestures that you need to perform while connecting your iPhone to the computer running the latest iTunes version, and follow these instructions:--> If you forgot the passcode on your iPhone, or your iPhone is disabled

Regards

Giulio

You are welcome