Share your experience!
can you try to boot safemode? just long press on the power button
does it work there?>
how about running Xperia Diagnostics. settings>about phone. check if the Led works.
try to perform a software repair using Xperia Companion
I haven't tried this myself yet. But if it only doesn't work because you muted. You can set a silence sound for the groupmessages in your whatsapp and unmute those groupapps. Just till there is a better fix.
If you need a sound to test with, I uploaded a 1 second silence.mp3
Try a software repair ....Led light while charging means Light is OK. Must be some issue with settings or Apps.