Double click doesnt open

Hi
I am using windows 7. Whenever I double click on any folder or single click while using internet browser, it doesn't opens. I have to right click and then select open in new window or tab.
When I start my system everything works fine, but then suddenly it stops working and I have to use right click option and select open in new window.
I tried all methods like deleting mountpoint2, antivirus, sfc/scannow but it doesn't works. Kindly help