Downgrading to Mountain Lion

Hi

Last June I purchased this MacBook Pro with Mac OS X 10.8. Mountain Lion, which was then upgraded to 10.8.5.

On 28 Oct 2013 after the release of Mavericks, I tried to upgrade to Mavericks, which failed and my system got irresonsive.

On the advice of Apple Support, I went to the local Apple Service Provider, who restored the system with Mavericks Developer Preview Recovery Updates losing all my data.

Now, I want to revert back to Mountain Lion by downgrading from Mavericks.

If it is possible, please help me out.

Thanks.

MAR