Theme installation

Hi, I had recently purchased Organic Food Drupal theme & then I followed your documentation. I tried installing demo full installation. It was showing full functional homepage except links I mean when I tried localhost/mysitename/user then it is showing 404 not found error and this is happening with all the links of the website except homepage. I had tried changing database user or created new database & I had also tried one more demo installation but didn't help then I had uploaded same demo installation on my one of the demo server It works like charm over there. But the same thing doesn't work on localhost. Please try to reply me at the earliest.