If, as I suspect, the OP does not want the numbers to print:

use strict;
use warnings;
my (%hash);
while (<>) {
  chomp;
  my ($text,$line) = $_ =~ m/(.+)(\d+)$/;
  $hash{$line} = $text;
}
print $hash{$_} . "\n" for (sort keys %hash)
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Since I use only the keys, no worries about missing line numbers.

Usage:

perl pm1.pl < input.txt > output.txt
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Update: I along with other respondents missed the fact that there could potentially be non-sequential line numbers in the data, and there might need to be blank lines created accordingly. Updated again to be a bit more perlish.

use strict;
use warnings;
my (@array);
while (<>) {
  $array[$2] = 1 if ($_ =~ m/(.+)(\d+)$/)
}
print defined $_ ? $_ . "\n" : "\n" for @array[1..$#array];
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