In some situation during SQL server setup access to VS media is required, if the media is not there then SQL setup may be blocked, here is workaround for this situation
1- Go to control panel programs and features select VS ultimate and then click Uninstall/Change.
2-Select Add or Remove Features then click download since media source is missing.
4-Start download and install all features
6-Install SQL server 2012 and happily have the installation succeed