You specified a prototype on a function (ReadDataInHash) that is called before it is declared.

Since the prototype is wrong and unnecessary, change
sub ReadDataInHash() { ... }
to
sub ReadDataInHash { ... }

A few general remarks about your code:

#!/usr/bin/perl
use warnings;
use strict;
[download]

Good!

if ($#ARGV != 4) {
 print "usage: run batch file 'run' not this one\n";
 exit;
}

my $wordfile = $ARGV[0];
my $textfile=$ARGV[3];
my $OutPutFile=$ARGV[4];
[download]

die "Usage: run batch file 'run' not this one\n"
  unless @ARGV==3;

my ($wordfile, $textfile, $outfile)=@ARGV;
[download]

open (IF1,"$wordfile")|| die "cannot open the file";
open (PF, "$textfile")|| die "cannot open the file";
open (OF,">$OutPutFile")|| die "cannot open the file";
[download]

The general rule of a thumb is to use low precedence logical operators for flow control. Also, we generally recommend using lexical filehandles and the three args form of open nowadays, althiough this is sometimes debated. Last, it would be nice to indicate in the error message which file failed to open and why. Oh, and there's no need to quote plain scalars. Thus:

open my $wfh, '<', $wordfile or die "Can't open `$wordfile': $!\n";
open my $tfh, '<', $textfile or die "Can't open `$textfile': $!\n";
open my $ofh, '>', $outfile or die "Can't open `$outfile': $!\n";
[download]

my $List1Ref=ReadDataInHash (*IF1);
[download]

You only need the to read from the wordfile in that sub, thus I'd pass the filename instead. Also, I see that later on you only dereference $List1Ref, to use it like a regular hash, so why not use a hash from the beginning (and call it sensibly, e.g. %words) instead?

my %words=ReadDataInHash($wordfile);
[download]

I'll soon look into ReadDataInHash():

sub ReadDataInHash()
[download]

As others wrote, you're indicating an empty prototype, but that

• differs from your actual usage (you pass an argument),
• you use the sub before it's declared, which causes the error you're incurring into.

Anyway prototypes are generally discouraged nowadays, except in certain situations. So just don't!

{
    my $x = shift;
    my %list1=();
    while (my $line =<$x>) {
        chomp $line;
        my @arr=split /\s/,$line;
        for (my $i=0;$i<=$#arr ;$i++) {
            if ($i==0) {
                $list1{$arr[$i]}={};
            }
            else{
                ${%{$list1{$arr[0]}}}{$arr[$i]} = 1;
            }
        }
    }
    return {%list1};
}
[download]

IIUC, you read from a space separated file, and you want to create a HoH where the "primary key" is the first word of the line, and the "secondary one" is given the value of each of the remaining ones, and all the values are 1. As a comment to your code, it is at times rather clumsy because of excessive referencing and dereferencing, and you should know that in addition to C-style for loops you have Perl-style ones for iterating over a list. In this case I'd use the latter, for maximum clarity. Taking into account all that has been written above, I'd rewrite the sub like thus:

sub ReadDataInHash {
    my $file=shift;
    open my $fh, '<', $file or die "Can't open `$file': $!\n";
    my %words;
    while (<$fh>) {
        chomp;
        my ($first, @rest)=split;
        $words{$first}{$_}=1 for @rest;
    }
    %words;
}
[download]

Ok, here it seems you want to

1. split on dots to get a list of "sentences",
2. print a successive number,
3. split each "sentence" on whitespace to get words,
4. compare words with those got from your "words file" and print them if found as the main term or print an informative string if they are a synonim of some main term.

I'm not entering into the details of your code, but

1. removing unnecessary and not clarifying intermediate variables,
2. simplifying some referencing-and-dereferencing acrobatics,
3. removing some calls to exists (because the keys either do not exist or have a true value),
4. using some lighter looping,

I'd rewrite it like thus:

Summing up, all in all I'd rewrite your script as follows:

As a last note, since you only print to the output file ($ofh in my version of your script) you may have well wanted to select it. OTOH, since this is in your words "a pattern matching exercise", you may have wanted to save yourself the hassle of managing input and output files yourself too, and resort to the ARGV magic filehandle and print to STDOUT, just passing the words file as a first argument. This would simplify your exercise to:

Here I didn't write a separate sub for reading from the words file into a hash, but I made a separate one for checking words, so that the main cycles can be simple enough to rely on default $_ without any risk of confusion. I also hid a loop into a map, which makes everything clearer IMHO. (Another minor change is that I removed the $title variable since you don't use it at all.) As a very last note, although many respectable Perl hackers would disagree, I think it would be clearer if instead of iterating over 0..$#sentences, one would maintain a counter him/herself:

Thanks a lot Blazar for your detailed tips..:). That really helps me learn perl better. Thank you once again!