use warning; # needs to be use warnings;

my $path = '/abc';

my $te = "$abc/texas"; # I assume you mean $path instead of $abc?  
my $mi = "$abc/michigan"; I assume you mean $path instead of $abc?
my $ha = "$abc/hawaii"; I assume you mean $path instead of $abc?
my $fl = "$abc/florida"; I assume you mean $path instead of $abc?
my $ke = "$abc/kentucky"; I assume you mean $path instead of $abc?

my $filename = "path/one.xls"; # needs to be my $filename = "$path/one.xls";

my $excl = Spreadsheet::WriteExcel->new($filename)
 or die "Cannot create new Excel file: $!" unless defined $excl; # this will not work

my $workbook  = Spreadsheet::WriteExcel->new('protected.xls'); # from module documentation (notice the ";" here)
die "Problems creating new Excel file: $!" unless defined $workbook; # from module documentation

# add the following after the part

my $book = $parser->parse($source);

for my $source ( '$te/te.xls', '$mi/mi.xls', # all files need to be defined with double quotes (e.g. "$te/te.xls")
         '$ha/ha.xls', '$fl/fl.xls', # with single quotes will not work
         '$ke/ke.xls' ){
    my $book = $parser->parse($source);

if ( !defined $book ) {
    die $parser->error(), ".\n";
}

##</code><code>##

if ($source =~ /1/) {
    $file  = $excl->add_worksheet('Texas');
}