network adapter not showing in device manager. even dell support assist does not detect missing wifi driver

HI, I have dell latitude E5470,the problem I am facing is that from last few days there is no wifi adapter showing in the device manager, the internet works when it is connected to ethernet, but wifi is not working. I have tried everything in my power to make it work, even the dell support assist is not recognizing any problem, please help. My whole job depends on wifi, it is causing real trouble in my life. When I download the official dell driver for wifi from the site, it says "This installation is forbidden by system policy. Contact your system administrator". I have tried every possible solution given on youtube.