What does that do? (I know it's untested code, but still...)

It comments out the current line. In the context of deleting lines, it's superfluous - a leftover of the original code.

--shmem

_($_=" "x(1<<5)."?\n".q·/)Oo.  G°\        /
                              /\_¯/(q    /
----------------------------  \__(m.====·.(_("always off the crowd"))."·
");sub _{s./.($e="'Itrs `mnsgdq Gdbj O`qkdq")=~y/"-y/#-z/;$e.e && print}

 #the first part of the code as the same last code i provided 
#!/usr/bin/perl -w



use strict;



print " please enter the domain name: ";



my  $targetdomain = <STDIN>;



my $susdate = `date -u "+%m/%d/%Y %H:%M"`;

my $char = "This Domain is Suspended at ";

chomp $targetdomain;



my  $file = "/home/adam/Desktop/hello";



rename $file, "$file.bak" or die "Can't rename file '$file': $!\n";



open my $in, '<', "$file.bak" or die "Can't read file '$file': $!\n";

open my $out, '>', $file or die "Can't write file '$file': $!\n";



my $block   = 0;

while(<$in>) {

    if (/^zone\s+"$targetdomain"/) {          
#here i want to start to deleting lines i think it will done by 
s// /; #by replacing the lines with an empty lines 
#then i need to increase the $block by 1 to add the first #open bracke
+t by using
 $block += () = /(\{)/g;
#then i want to make something like condition if the block #variable i
+s exist add one also to block and then  continue #deleting lines 

if ($block) {
s// /;
#or if it find a closed bracket decrease the $block by 
 $block -= () = /(\})/g;
#and if the block equal to 0 stop deleting lines 
#then print the output
[download]

my $comment = 0;
my $block   = 0;

while(<$in>) {
    if (/^zone\s+"$targetdomain"/) {
        $comment++;
        $block += () = /(\{)/g;
        # print $out '// '.$_;
        next;
    }
    if($comment) {
        $block += () = /(\{)/g;
        s!^!// ! if $comment or $block;
        $block -= () = /(\})/g;
        $comment = 0 unless $block;
    }
    print $out $_ unless $comment;
}
[download]

by the way the code you provide me didn't work

Which part didn't work? did you add some print statements to your code to see what each variable holds at each state of execution?

I suspect your main problem is

my  $targetdomain = <STDIN>;
[download]

$targetdomain is a line from STDIN complete with the newline char. This will match your targetdomain only if it is written as

zone "foo.bar.com
" {
[download]

and only if you read the file as one chunk and do a multiline match. So change that to

chomp (my  $targetdomain = <STDIN>);
[download]

to remove the trailing newline.

update: To get help without suspecting, it is best to provide a complete set of data: input, program, expected output, actual output. Do so with the snippet that "didn't work".

--shmem

_($_=" "x(1<<5)."?\n".q·/)Oo.  G°\        /
                              /\_¯/(q    /
----------------------------  \__(m.====·.(_("always off the crowd"))."·
");sub _{s./.($e="'Itrs `mnsgdq Gdbj O`qkdq")=~y/"-y/#-z/;$e.e && print}

i mean didnot work didnot perform what i was expected to delete lines from file
as you provide here :

my $comment = 0;
my $block   = 0;

while(<$in>) {
    if (/^zone\s+"$targetdomain"/) {
        $comment++;
        $block += () = /(\{)/g;
        # print $out '// '.$_;
        next;
    }
    if($comment) {
        $block += () = /(\{)/g;
        s!^!// ! if $comment or $block;
        $block -= () = /(\})/g;
        $comment = 0 unless $block;
    }
    print $out $_ unless $comment;
}
[download]

you comment print statement to deny the comments and then use print $out $_ unless $comment; which is completely logical
but when i run it didn't delete the zone .....,
i think i need to provide something that written inside a loop to replace the lines of the zone with space like

s///;
[download]


what do you think about that?
thanks shmem for your great support
warm regards