Hi @Whiteflower,
Welcome to the community.
I'm sorry to hear this. I recommend that you disable developer options in your device. You will find the option to do so under: Settings > About phone > Developer > Off. If you can't find developer options in the settings menu, the developer options are already disabled.
I'd also recommend that you try and reboot your device to safe mode to see if one of your downloaded apps may be causing this behavior. In safe mode all of your downloaded apps are disabled, that doesn't mean they are gone, if you restart your device as normal all your apps will be restored.
If the same behavior still persists I would recommend that you perform a software repair using Xperia Companion on your device.
Let me know how it goes!
