The following should do what you want. Note that the sort is alphabetic instead of numerical - you may want to change to numerical if you know for a fact that all keys will be numbers.

use strict;
use warnings;

my $p;
my %file_attachments = (
    '1'  => { 'price' => '10.00', 'desc' => 'the 1st test'},
    '2'  => { 'price' => '12.00', 'desc' => 'the 2nd test'},
    '3'  => { 'price' => '13.00', 'desc' => 'the 3rd test'},
    '4'  => {
          '' => '',
          '35' => 'D',
          '11' => '3104052',
          '63' => '0',
          '167' => 'FUT',
          '200' => '200512',
          '1' => '2',
          '44' => '112.55',
          '55' => 'XEURFGBM0F2005Z',
          '50' => 'portwaretrader1',
          '40' => '2',
          '57' => 'RISKGATEWAY',
          '15' => 'USD',
          '38' => '1',
          '52' => '20051118-07:31:46',
          '59' => '0',
          '60' => '20051118-07:31:40',
          '34' => '37',
          '56' => 'EXLINK_CAMPBELL',
          '49' => 'CAMPBELL_EXLINK',
          '10' => '170',
          '54' => '1'
    }
);

for (sort keys %file_attachments) {
    print "'$_' =>\n";
    $p = $file_attachments{$_};
    print "    '$_' => '$p->{$_}'\n" for sort keys %$p;
    print "\n";
}
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