thanku vry much for ur reply, here i am attaching the shapshot of my mobile.
Before and after downgrading i did Factory restore .
And i am very sorry my mobile model is GT-I9300 which i bought in UK -3 Network. ( just now i noticed this forum is for I9305).
Do i need to Rooting or custom ROM installation or sumting like that?
PS shopshot order 1)mainmenu--> 2) debug screen --> 3)Phone Control--> 4)menu does not exist
It worked fine on my friends S3, root required though.