Trying to wipe hard drive before trade in on MacBook Pro 2012. Internal HD and HD Data drives are now missing. There is no HD drive for me to select when trying to reinstall Catalina OS X?

You’ll want to use Disk Utility to erase and format that HDD disk to GUID/GPT partitioning with an HFS+ macOS Journaled file system. That should make that HDD visible to the installer, if the HDD was erased.

And at this point, the HDD storage has already been erased, so arguably you’re already done here… installing macOS overwrites more of the contents, if the HDD wasn’t previously encrypted.

Dale_L_S wrote:

I in big trouble here. I tried to follow the instructions on this forum to wipe all data from the internal HD using Disk Utility. It seemed like that was successful.

However, when I tried to reinstall Catalina OS X, once I accept the conditions, it asks me to select a drive to install to, and there is no drive available to select (it is empty).

What I have under the Internal disk utility is APPLE HDD HTS545050A7E362 Media. 500.11 GT Sata Internal Physical Disk. But again, when I try the OS installer, no internal HD disk is visible to allow me to reinstall the OS.

I am now in Internet Recovery Mode. The only things I can access are my WiFi and OS X Utilities.

Can anyone help me?

How to erase your Intel-based Mac - https://support.apple.com/en-us/HT208496

How to reinstall macOS from macOS Recovery - https://support.apple.com/en-us/HT204904

See if this applies:

How to erase an Intel-based Mac - Apple Support

If you don’t see Macintosh HD in Disk Utility

Your built-in startup disk should be the first item

listed in the Disk Utility sidebar. It's named Macintosh HD, unless you

changed its name. If you don't see it there, choose Apple menu  >

Shut Down, then unplug all nonessential devices from your Mac and try

again.

If your disk still doesn't appear in Disk Utility, or Disk Utility

reports that the erase process failed, your Mac might need service. If

you need help, please contact Apple Support.

Follow these instructions:

What to do before you sell, give away, or trade in your Mac - Apple Support

And in addition to the above reply, that Apple HDD HTS545050A7E362… storage device is your hard disk.