I have lost my phone (sony ericssion g-502) & how can i block it

I think you can try to use LEO Privacy, it has a very useful feature- Anti-theft. When your phone lost, you can use it to lock your apps, wipe your phone data and track your phone. Highly recommanded. LEO Privacy Applock Boost Hide Android Apps on Google Play

For protecting and finding back your lost phone, I would recommend an app called LEO Privacy:You can use your preserved number to send the commands to your lost phone and then find it.
LEO Privacy Applock Boost Hide Android Apps on Google Play

First thing to do is notify your supplier..i.e. t mobile.orange,and they will block your phone.

Hope i`ve helped.