You need to show the actual code you tried. Much, much better is to rework your code into a stand alone test script so we can run exactly what you are running with the same data. Something like:

#!/usr/bin/perl
use strict;
use warnings;

my $keyword = 'file';

# Search for the key pattern in the file information.
while (defined (my $line = <DATA>)) {
    next if $line !~ /\b\Q$keyword\E\b/;
    
    print "Found key word $keyword on line $.\n";
    exit;
}

print "Keyword not found\n";


__DATA__
Hi, I am a newbie to perl. I am trying to pass the filename and search
+ for a
keyword in that file and if found print that line else print not found
+ message.
However though my file has the keyword I get not found message.Please 
+help.I
[download]

Prints:

Found key word file on line 2
[download]

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