You need to open a raw file in order to summon ACR (Adobe Camera Raw). Otherwise, you won't see it.
Hmm, well that was true, right up to the last update when they added camera raw as a filter. But that requires a subscription to photoshop CC.
There are ways to summon camera raw even if you don't own any raw files.
In bridge select any tiff or jpg file then hit ctrl-r or command-r former is windows and latter is mac.
In Photoshop File>Open Select a tiff or jpg image then in the file type drop down box select camera raw.
In photoshop CC camera raw now supports png, which will work with the above examples.
Thanks for chiming in, Silkrooster. I stopped at CS6, so I opted not to subscribe to the Cash Cow, ever, so I had in fact forgotten all about the ACR filter option in Photoshop CC.
The OP neglected to specify his version of Photoshop. If the OP does not subscribe to CC either, then my reply in post #1 remains valid.
No problem... Sometimes I forget others may not have a need or want to upgrade.