Camera problem on my K810

Hello guys,
Recently i am haing problems with the camera button. When i press the button it focuses only but does not take photos. so i went to the >*<<*<* to check for any keyboard problems and i pressed the button and the message camera focus and camera capture did not appear. However, after i pressed a random key (in this case i pressed the button 1) and i pressed the camera button again and it showed that the button is responding to the camera focus and camera capture function. So i tried to use it and it worked. Then after a day, it doesn't work again so i had to go back to the >*<<*<* again and repeat the process again... How do i fix this?

Thanks in advance.

PS: i have reflashed my phone a lot of times but the issue persist.