#!/usr/bin/env perl

use strict;
use warnings;

my $lines_per_block = 4;
my $wanted_id = 'id2';

while (my $joined_block = join_block_of_lines($lines_per_block)) {
    next unless $joined_block =~ /^$wanted_id/;
    print $joined_block, "\n";
}

sub join_block_of_lines {
    my ($lines_per_block) = @_;

    my @block_lines;

    for (1 .. $lines_per_block) {
        my $line = <DATA>;
        return '' unless defined $line;
        $line =~ s/\s*\n$//;
        push @block_lines, $line;
    }

    my $joined_line = join ' ' => @block_lines;

    $joined_line =~ s/\s*\t\s*/ /g;
    $joined_line =~ s/^(\S+)\s+(:)\s+/$1$2/;

    return $joined_line;
}

__DATA__
    id1 : /a text lies here/ 
add name: new add1
ph  no: new phone1
country: new    country1
id2 : /some  other text lies here/ 
add name:   new add2
ph no: new  phone2
    country: new country2