use strict;
use warnings;

my $line;

while (<DATA>)
{
   chomp;
   if ( (/:$/../^\s*$/) =~ /^\d+$/) #exclude endpoint.
   {
       s/\s,\s/,/;
       $line .= " $_";
   }
   elsif (defined $line)
   {
       $line =~ s/^\s*//;
       print "$line\n";
       $line = undef;
   }
} 
print "$line\n" if defined $line; # just to be sure
                                  # all output is done

=prints
99~Arun~Kumar~Mobilenum: 1234-567,from Earth Human
98~Mahesh~Babu~Mobilenum: 5678-901,from Earth Human
98~Mahesh~Babu~Mobilenbbb: 5678-901,from Earth Human
=cut


__DATA__ 
99~Arun~Kumar~Mobilenum:
1234-567 , from Earth
Human


98~Mahesh~Babu~Mobilenum:
5678-901 , from Earth
Human

98~Mahesh~Babu~Mobilenbbb:
5678-901 , from Earth
Human