02-18-2013 04:51 AM
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Have you tried a Battery Pull Restart ? Please do it by removing the Battery while your device is Powered On , wait for a min. then re-insert it back .After reboot see if you are able use those keys .
If problem persist then you have to recall if you have recently Installed any application after which this problem arise , think carefully it may be an application , theme or even a wallpaper . If it is then Uninstall that particular application from Options > Device > Application Management > Delete those third party application that you think might be responsible .
Finally perform another battery pull reboot, after device restart see if problem resolves.
02-18-2013 12:58 PM
You need to provide a little more information , As I asked have you installed any apps or somthing after which this issue arised . Or it happen all of a sudden .
Because it might be possible that its a Software / Hardware issue , to rule out any software issue you can try an OS Update / Reload . If problem continues then you have to contact your Service Provider .