Amicodu,   Sorry for the delay, got a little behind because I was away.   I do not see your wireless adapter listed. It may have failed or come loose. If you're under warranty, contact Dell tech Support.   If you're not under warranty, the manual can be found HERE and go to page 45.     Rick
I scanned many times but it still could not detect any wireless adapter. [IMAGE]   And then I tried to uninstall all the adapters and install the latest adapter that I had downloaded from [URL]     [IMAGE] Both of them I have tired to install and they were successfully unzipped , but when I scanned the network adapters in the Device Manager again, there was no change, everything back again.[IMAGE]  And I also got this [IMAGE]   When I clicked it, it became like this [IMAGE]        
Dell Inspiron 14r 5420 cannot detect wireless adapter