On my Nokia Lumia 720, why has the back,search and menu stopped working?

[Windows Central Question]

my nokia lumia 720 back,search and menu stopped working..

i have updated the phone yet nothing changes in the keys.they cant work.

 

[gpobernardo]

Re: my nokia lumia 720 back,search and menu stopped working..

i have updated the phone yet nothing changes in the keys.they cant work.

Looks like some form of hardware failure. Have it checked in an accredited service center.