Macbook Pro Wifi: No hardware installed I have recently been getting a "No hardware installed" error when I click on my wifi. I have tried resetting the SMC, resetting PRAM, reattaching the cables in the electronics of the computer. Now I am stuck for solutions and I think maybe I need to get a new wifi cable? It is a Macbook Pro 15" early 2011 running OSX El Capitan.
...reattaching the cables in the electronics of the computer.


I am assuming by this statement, you have opened up your Macbook for whatever reason.  Did you do any sort of service?


Try reseating the Airport adapter - remove it completely and reinstall it.  

There are 4 cables that go to this adapter.  Three are the antenna cables (J0, J1, and J2) and the interface to the logic board (right)

In addition to that, you have the interface cable that connects it to the logic board (below).  Notice the two connectors at each end.



You have 4 things to check:


The Airport card connector
The cable connectors
the cable itself
The logic board connector


You will have to look closely.  If you did any service to the MBP where removing these components was necessary, you may have damaged them either during removal or installation.  

The other scenario is that your Airport card simply failed; it happens.

If you damaged either the Airport card and/or the cable, you will have to replace them.  The good news is that they are available on the open market for less than $50


Airport Bluetooth Card 661-5867 
Airport Bluetooth Flex Cable 821-1311-01


If you damaged the connector on the logic board, you will need to have it fixed, the logic board replaced, or get a USB Wifi Adapter like these Netgears (I have personally used them with Macbooks quite successfully).