Rooting problem Galaxy y duos

[jim1924]

Hey guys.I need your help.I have a samsung galaxy y duos and i have the following problem.I have rooted my phone and i wanted to be able to install apps that claimed to be incomatible in playstore.So the only file i changed was the build.prop from system.I changed only the ro.product.model from Y Duos to Nexus S in order to be able to install all apps.Only that.And the problem is that the phone cannot start.When it shows the samsung logo it vibrates and restart itself and then the same until i pull off the battery.What do you suggest guys?How can i restore it to factory defaults?And do you know how can i have access to this file without opening the phone?