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I suggest that you perform a software repair on your unit via Update Service:
http://www.sonymobile.com/global-en/tools/update-service/
Download and install SUS at your PC, follow the instructions that appear.
But if the top part still doesn't work, I suggest that you visit nearest service center so a technician can examine your unit. You can contact your local support team for further information about nearest service center and/or how to proceed with this in the best possible way:
http://www.sonymobile.com/global-en/support/contact-us/contact-info/
