ITC avail or not?

yes we are GTA AND RENTING OF IMMOVABLE PROPERTIES.

sir, We filed GSTR1 JULY-17 NIL RETURN BUT WE ARE HAVING TRANSPORT BY ROAD UNDER GTA AND RCM PAID BY OUR CLIENTS LIKE GODREJ, HINDUSTAN LEVER.  HOW CAN WE FILE GSTR1 JULY REVISED RETURN.

You can't file Revised GSTR-1. 

But your customer like godrej, Hindusthan etc.. should mention the GTA ( RCM details ) in their GSTR-2. Once they file their GSTR-2, those details will be autopopulated in your GSTR-1A. You have to accept the tranactions which you actually forgot to give in your GSTR-1.