Initially I tweaked the lens back and forth, as has been suggested, and it worked for a while (temporarily) but I soon discovered that the issue of non Auto focsus was not resolved after all. I too then went into the ‘Menu’ setting, looked for ‘Buttons’, and assigned the AE/AF button to AF-ON. Now all I have to do is depress the AE/AF button to Auto Focus, you will hear the familiar beep sound when your image is focusesd release the AE/AF button once focused and take your picture in th usual way using shutter release - PROBLEM SOLVED. Hope this helps you guys! Admittedly it doesn’t explain why it no longer auto focuses with a slight depression of the shutter release as it used too, for for now at least, I am quite content to have found a work around.