Flash Player is pre-installed in Google Chrome (Windows7), but not enabled and it is also not there among the list of plug-ins.
As we don't have any control over the installation process on Chrome, you'd need to seek help in the Chrome forums.
That said, this seems very odd.
Type the following in the address bar:
Click Details and expand the list.
Scroll down, and you should be able to find Adobe Flash Player in the list.
If it's not there, I'd remove Chrome and just download it again from Google.
Also, do you have any security or privacy software (maybe from a not-so-mainstream vendor?) that might helpfully remove Flash Player for you?