It looks like the shipping triggers got overwritten with blank values. You should replace the lines in your store cart page with those same lines from the downloaded version of the page. Instead of looking like this:
if (false && ()) {
They should look like this:
if (true && (("USPS"=="USPS")&&(isset($_SESSION["WA_Store_Cart_USPS_Quote"]))&&(floatval($_SESSION["WA_Store_Cart_USPS_Quote"]) != 0))) {
You will need to do this for the USPS, FedEx and UPS shipping rules. It does not matter if you are not making use of them, if there are syntax errors in them you will not be able to display pages that rely on this included cart file.