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My viberation stopped
I'm sorry to hear this. 
I would recommend that you make sure that you do not have to device in STAMINA mode as this will disable vibration. You can turn off STAMINA if you go to: Settings > Battery > STAMINA mode > Never.
If you are still experiencing this I recommend that you test the vibrations function in diagnostics. You can do this if you go to: Settings > About phone > Diagnostics > Test > Vibration. How does the vibrations function behave in this test?
Let me know how it goes! 
@Titou56, I'm sorry to hear this.
Have you made sure that you don't have STAMINA mode activated?
I disabled the stamina mode to make sure the problem is not there. Is a phone reset correcting the problem?
@Titou56, then I would recommend that you reboot your device to safe mode to see if this behavior is caused by one of your downloaded apps as these are temporarily disabled in this mode.
If you are still experiencing the same behavior, I'd recommend that you perform a software repair using Xperia Companion.
Keep me posted how it goes.
Thanks for watching my problem, safe mode has not changed anything. If I use my companion do I lose my personal data?
Reset the phone can't help. Your vibration motor is broken mine broken too. You can buy a new one for about 7eur and change by your self it easy.
@Titou56, yes performing a software repair using Xperia Companion will reset your device deleting any personal data stored on your devices internal storage. You can backup using Xperia Companion as well before your reset your device.
@sgizmo, the reason I recommend software repair using Xperia Companion is to rule out that there are any software related causes of this behavior.