Hi @David69dh, sorry to hear about what has happened. 
If you can't remember the screen lock that you set on your device, you will need to perform a software repair using Xperia Companion. Do note that that this will delete all data stored on the internal storage of the device.
You will also need your Google credentials to be able to login to the device after the reset, due to it having the Google Device Protection feature.
Let me know how it goes!
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