Kindle not recognised under windows

I'm new here. I hope it's OK form to jump onto an older thread here. If not, and my addition should be moved or split, I apologize and I hope a mod or admin will do that.

Here's my situation.

I have a Kindle Paperwhite and I won't show up on computers. One is running Windows 8 and another is still on Windows 7. I can use the USB cable and both will charge my Kindle, but neither recognize it as a drive.

Ultimately my goal is to synch my Paperwhite with Calibre, but that's a battle for another day.

TIA for any help!