I have set all ports to '0' in start and then i give high signal on P1.7 EXTERNALLY, which further executes the rest of program. and P1.7 does go high even its been initialised as '0' in the start.and the logic works.
If you look at the picture of a port in "the bible" here I go again "read" you will see that if you write '0' to a port pin and externally apply Vcc directly (through a switch) to the pin, most likely, POOF goes a transistor. With that transistor out of the way, you can, of course read a '1' from a port to which you have written a '0'. HOWEVER, you will keep wondering "did anything else get damaged?".

The requirement of setting a port pin to '1' in order to be able to read it is ELEMENTARY. Thus for your own sake get to reading "the bible" before you do more damage.

I am so very sorry, I know it is not "in" to read before acting, and probably I am going totally agains your grain, but, in this case, - again I am sorry - it is required.

Erik