Awhile ago my navbar violently shuttered and has stopped working ever since. The home button nor the multitasking nor the back button seem to work. I tried restarting and even factory resetting but it doesn't seem to help. I don't think my phone is water damaged as I'm very careful with not getting my phone wet. Navbar is only working in landscape mode
Start troubleshooting by restarting your phone into safe mode, this will disable all installed 3rd party apps. If the problem is resolved then one of your installed apps is causing this issue and you have to figure out which one. Start by uninstalling those apps you installed recently.
I'm not sure if it's a software or hardware issue now. The only way to know is by performing a software repair using Xperia Companion. This will do a clean installation of the latest firmware and will also wipe your internal memory. Don't forget to backup using Xperia Companion, but preferably without adding apps or settings to the backup. Test the navbar area before you install any apps.
Follow the steps given in blue links, and keep us updated.
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