use File::Find;
use File::Copy;

sub find_copy_rename {
  # THIS FUNCTION IS NOT THE ONE CALLED BELOW
  # WHY IS IT HERE?

my @dir = $fixed_path; 
  # HERE YOU ARE ASSIGNING A SCALAR TO AN ARRAY
  # It will work, but why are you doing it?

my @get_directory = substr($fixed_path,-12);
  # HERE YOU ARE ASSIGNING A SCALAR TO AN ARRAY
  # It will work, but why are you doing it?
  # Why are you using the last 12 characters of $fixed_path?
  #    How do you know that is what you want?

my $get_each_directory = @get_directory;
  # HERE YOU ARE ASSIGNING AN ARRAY TO A SCALAR
  # AFTER THIS '$get_each_directory' WILL EQUAL THE NUMBER 1

my $dir = @dir;
  # HERE YOU ARE ASSIGNING AN ARRAY TO A SCALAR
  # AFTER THIS '$dir' WILL EQUAL THE NUMBER 1
  # PROBABLY THIS IS NOT WHAT YOU WANT

my $current_path = 'C:\\temp\\';

# HERE $dir == 1, so this will always FAIL
if ($File::Find::dir ne $dir)
    {
        $File::Find::prune = 1;
        return 0;
    }
  # IT LOOKS LIKE YOU WANT TO ONLY LOOK IN THE DIRECTORY
  # ASSOCIATED WITH $fixed_path.  IF SO, CONSIDER USING
  # readdir() or glob() RATHER THAN File::Find

    return 0 if ($_ !~ /\.rtf$/);

    copy($File::Find::name, $current_path.$_) or die "Failed to copy $_: $!\n";
    return 1;
}

find(\&process_files, $dir);
  # WHERE IS THIS FUNCTION 'process_files'?

my @process_file = &process_files;
  # NOW YOU ARE CALLING 'process_files' AGAIN.
  # ALMOST CERTAINLY WRONG
  # Functions used in File::Find do not return a list of files
  # You can append to a list in the function called from
  # File::Find

my $get_files = grep { !-d } @process_file;
# NO, THIS IS WRONG
# HERE 'get_files' IS SET TO THE _number_ OF NON-DIRECTORY
# FILES IN THE ARRAY @process_file
 
  foreach my $get_files (@process_file) {

       my $newfile = $get_files;

       $newfile =~ s/\$mrn.$get_each_directory.'.'.rtf$/word1.rtf/;
       # THE VARIABLE '$get_each_directory' IS NOT IN SCOPE HERE
       # (AT LEAST IN THE CODE WE SEE)
       # THE LEFT-HAND SIDE OF YOUR SUBSTITUTION MAKES NO SENSE
       # IT IS ALREADY QUOTED SO YOUR USE OF ' and . IS ERRONEOUS


  if (-e $newfile) {
    # YOU (MAY) NEED TO INCLUDE A DIRECTORY HERE
    # UNLESS $newfile INCLUDES A DIRECTORY OR YOU
    # ARE LOOKING FOR IT IN THE CURRENT DIRECTORY
    

       warn "can't rename $get_files to $newfile: $newfile exists\n";
    } elsif (rename "$newdir/$get_files", "$newdir/$newfile") {
    # WHAT IS '$newdir' ????
      print "file was renamed to $newfile\n"
    } else {
      warn "rename $get_files to $newfile failed: $!\n";
    }
 }

##</code><code>##

my @rtf_in_dir = glob("$dir/*.rtf");

##</code><code>##

use File::Find;
my @rtf_in_subddirs;
sub wanted {
  if (/\.rtf$/) {
    push @rtf_in_subdirs, $File::Find::name;
  }
}
find(\&wanted, $dir);