I received a 1099-R but I did not take any monies, I left the monies there when I left the company. It is still in a 401K at this moment, just sitting there

Then what is the 1099-R for? What is the code in Box 7?

In box 7, the code is G

A code of G in  box 7 indicates that it was a rollover. So it must have been rolled over into another tax free account.

do I still list this on my tax return?

yes you do report it.. You must report each and every 1099-R that you get, no matter what it is for.