Chevrolet Suburban 2005 No communication

Hey everyone

I got a Chevrolet Suburban 2005 with the following VIN : 3GNFK16Z15G105902

The problem i am facing is my car shuts down as soon as it starts. When i try to diagnose it using Tech 2, it doesn't communicates with any of the modules. Recently it used to communicate and start normally until i sent it to a workshop for my 4WD repair where they lost my original keys and got the car in this shape. Can anyone help me sort out this issue?

Thanks in Advance