please use
<code>..</code> tags so your code is easier to read and copy/paste.
you have a couple of problems:
zero, you are missing "w" from your alphabet.
one, you should chomp $hladane immediately after reading it rather than at the end of the while loop.
two, your assignments $alphabet[$nummer] = $slovo are backwards, and you are slowly undefing each element of @alphabet.
consider:
use warnings;
use strict;
my @alphabet = (
"a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k", "l", "m",
"n", "o", "p", "q", "r", "s", "t", "u", "v", "w", "x", "y", "z"
);
my $nummer = 0;
my $slovo;
print "Tell me your pass (only small alphabet only ONE a-z)";
my $hladane = <STDIN>;
chomp $hladane;
print "$alphabet[$nummer] \n";
$slovo = $alphabet[$nummer];
while ($slovo ne $hladane) {
$nummer = $nummer + 1;
print "$alphabet[$nummer]\n";
$slovo = $alphabet[$nummer];
}
print "GOTCHA $hladane !!! \n";
