Sometimes your intellisence stops working in Visual Studio.
The problem mostly arises when you install some add-in or uninstall the add-in. I faced this problem When I un-installed re-shareper. All you have to do to get back your intellisense is
just close your Visual Studio.
Navigate to Windows -> run, and type “devenv /resetsettings” without double quotes. This will reset the settings completely. You can have your intellinsence back this way. You can also write “devenv /resetsettings” from your command prompt.