#! usr/bin/perl
#use Win32::Gui;
 use Win32::GuiTest qw(:ALL);
 use strict;
 
my $window = FindWindowLike( undef,"[Install*.*|*Setup.*]","" );
    
        for($window) 
        {
            SetForegroundWindow($window);
            
            my @hwnds = GetChildWindows($window);
            foreach(@hwnds)
            {
            SetForegroundWindow($_);
            my $var = GetWindowText($_);
            print "shayak";
            print $var;
            my $class = GetClassName($_);
            print $class;
            #my $child = GetChildDepth(GetDesktopWindow(), $_);
            #print $child;
            if ($class eq ["*RadioButton"])
            {
        
                my $id=GetWindowID($_);
                print $id;
                #CheckButton(GetWindowID($name);
                if (WMGetText($id)eq(["*agree*" ]or ["*accept*"]))
                {
                    CheckButton($id);
                }
                else
                {
                    SendKeys{"TAB"};
                    SendKeys{"UP"};
                }
            }
            #PushButton("Next" or "Agree" or "Install" or "Yes" or "Fi
+nish" or "Done");
            SendKeys("~");
            }
        }
[download]

Seriously, your program can never have worked (except by accident). Start learning Perl and learning how to read documentation.

Where in the documentation for Win32::GuiTest did you find the following usage?

FindWindowLike( undef,"[Install*.*|*Setup.*]","" )
[download]

This is not how it is shown to be used and can never work as intended.

You need to stop guessing and making things up and you need to start learning programming, and how to read documentation, and then learn Perl.

Update: Weakened first sentence

Im just including a regular expression as i needed a window which says installation or setup or something similar thats why the * and it can have any extension so *.* . But this thing was working before..