is there a filename.state.dir file too? if so based on the link from marto this may work;

 use strict;; use warnings; 
 use Fcntl;   # For O_RDWR, O_CREAT, etc.
 use SDBM_File;

 my $filename='filename.state';
 my %hash; 
 tie(%hash, 'SDBM_File', $filename, O_RDWR|O_CREAT, 0666)
   or die "Couldn't tie SDBM file 'filename': $!; aborting";


 use Data::Dumper; 
 print Dumper(\%hash);
[download]

I would make a copy of the two files first, then run off of the copies, just to make sure.