Hi @Неработаеткнопка, welcome to our forum and I'm sorry to hear about this.
Your question has been translated to English since this is an English only forum. Please post any replies in English.
If the power button doesn't work on the device, you can try and perform a software repair using Xperia Companion just to make sure that the software in the device is not the cause of this.
Do note that if the phone is powered off and you can't power it on since the power button isn't working, you will not be able to create a backup and all data stored on the internal storage will be deleted when performing a software repair.
If there is no change after the software repair has been completed, your device will need to be examined at an authorized service centre and your Local support team will assist you further with this and answer any questions you may have regarding warranty, local service routines and so forth.
Let me know if that helps!
