404 Error During Checkout Process

Hi, I’m having a problem with my eStore plugin after my site got hacked. My website [www.presalecentral.net] was recently hacked and had malware inserted into it. After noticing this, I quickly paid for a malware removal service which got rid of all the malware. However, I soon noticed that the malware had affected some of my site’s functionality because my site’s custom background was now a basic background. The malware removal website fixed the background issue for me, but now I see that my WP eStore plugin has possibly also been affected. Now when I click on the Add To Cart button and then the Paypal Checkout button I am given a 404 error [http://presalecentral.net/wp-content/plugins/wp-cart-for-digital-products/eStore_payment_submission.php]. It says that the following file does not exist, but it does exist because I manually reuploaded all of the plugin’s files after the hack. I’m guessing that the malware somehow affected the plugin’s functionality because I don’t think that this file or the plugin is suddenly out of date. Can someone please help me with this? I can provide FTP access if needed. Thanks in advance.