Q: Issue with internal display after El Capitan 10.11.6

I have an old MacBook Pro 17" and is well taken care of with minimal use as of late since I have my work laptop. However, after I updated to 10.11.6 couple of days ago and I don't see the internal screen anymore. Today, I have sometimes to dig around and come to find that in the hardware management does not even list the internal display. I am firmly believe that my hardware is working fine and I am wondering if anyone else contracted with this issue and there is a fix for this.  Thanks.