Maybe this works, although somehow you didn't tell what your problem is...

#!perl -w
use strict;

print "Author to search for:";
my $search = <STDIN>; chomp($search);

my $totalprice = 0;
my $found = 0;
my @info = ();
my ($title, $autor, $genre, $price);

open (INPUT, "books.txt") or die "Error: $!"; # always check for error
+s
while (<INPUT>){
  chomp $_;
  ($title, $autor, $genre, $price) = split (/:/,$_);
  if ($search eq $autor) { # eq for stringcompare, == for numerical
    $totalprice += $price;
    push (@info, [ $title, $genre, $price]);
    $found++;
  }
}
print "$found books by $autor were found...\n";
print "They are:\n";
print "\tBook Title\t\t\tGenre\tPrice";
foreach my $info (@info){
  print join("\t", @$info), "\n";
}
print "\tTotal price of these books by $search is   $totalprice";
close INPUT;
[download]

Best regards,
perl -le "s==*F=e=>y~\*martinF~stronat~=>s~[^\w]~~g=>chop,print"