my mobile nokia lumia 635 has software problem. when i switch on the mobile it is showing

[WPCentral Question]

Error:unable to find a bootable option. press any key to shut down.
the above mentioned message is coming when i switch on the mobile. i went to the shop they are saying software problem. how to solve this issue. please suggest what to do to rectify this problem.

 

[Rising Mos]

Windows phone recovery tool might help.