mac internal hard drive not showing up in disk utility

I won't lie to you, this unfortunately seems to be your case. In my case my volume header wasn't functioning normally. Here I can only think of 2 possibilities: If you did all of that and your HDD still refuses to be recognized, we know that the problem is in the HDD itself. Another thing that may sound stupid but worth trying is - making sure your HDD is screwed in properly. If you don't, you might want to purchase one or even buy a replacement SATA cable for your Mac. There's also a chance the wire itself is damaged, so if you have a HDD enclosure try plugging the HDD into that and see if it gets recognized in disk utility. So make sure all the wires are plugged in firmly. There's always the off chance that some SATA cable came loose, and you simply need to plug it back in. We need to find what the issue is first to troubleshoot it. The next step will be pinpointing the issue. This can happen because of a few reasons. The folder with a question mark tells us that your Mac cannot find a startup folder. Let's start off with the meaning of this sign.

Unplug you battery from your Mac while poking around its internals.

My method involves lots of praying and does not contain any super-secret terminal codes.

Contact Apple support, and you might receive better instructions. I never was, and am not an Apple technician. This comes from experience involving talking to lots of Apple cutomer support representatives and many community members. I hope you have a backup (unlike stupid me) otherwise it will be an extreme P.I.T.A. What a coincidence, I just had this issue with my SSD (a month or two ago).

Mac internal hard drive not showing up in disk utility