Please help

May we know why you're not happy with Mountain Lion? If you have a Snow Leopard dmg burned somewhere ( get one if needed ), I can't think of a reason why you couldn't just install and use it. If that's what you really want...

 

Mac OS X 10.6 Snow Leopard does not have drivers for 2012 Macs, thus it is not possible to install Mac OS X 10.6 Snow Leopard on 2012 Macs, which is sad, but that is the way it is with Mac OS X.
And also know, that the Mac OS X 10.6 Snow Leopard Upgrade DVD normally only has 10.6.3 on it, thus it would not even work with 2010 Macs, as they had their own special builds of 10.6.3 and later.

You are stuck with OS X 10.8 Mountain Lion now, unless you get your hands on a refurbished 2011 Mac (except the 2011 MacBook Air).

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