Hi @Xperiaxa1925020, sorry to hear that. 
How is the speakers working in the inbuilt test in the device? You can find the test in Settings > Support > Xperia tests > Media.
You can also try and play something through the speakers while the device is rebooted in safe mode, so we can make sure that no downloaded applications is the cause of this.
Let me know if that helps! 
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