Downloads suddenly failing no reason?

[lj111970]

Can someone PLEASE help me???

This is my site
http://ljgdesign.com

I sell items that become immediately available in download format upon payment by the customer via Paypal. My site has been working fine and no issues until suddenly today.
I looked back and it seems Wednesday was the last sale that was processed and it went fine. Yesterdy I made a sale as well as today and both times the downloads will not work.
I have changed nothing and have not even been on my site since Tuesday and have gone through my admin and everything seems ok. The name files are all correct, permissions are correct on the folders, settings accurate and enabled and the files are actually on the server. However when the person clicks the "download" button they get the error shown in the image below.

I have contacted my site host and asked them to check the database and they insist everything is accurate from their end.
A friend of mine was helping me and she said my error log showed this.

PHP Fatal error: require() [<a href='function.require'>function.require</a>]: Failed opening required 'includes/templates/template_default/templates/tpl_download_default.php' (include_path='.:/usr/lib/php:/usr/local/lib/php') in /home/ljgdesi/public_html/includes/templates/template_default/common/tpl_main_page.php on line 119
PHP Warning: require(includes/templates/template_default/templates/tpl_download_default.php) [<a href='function.require'>function.require</a>]: failed to open stream: No such file or directory in /home/ljgdesi/public_html/includes/templates/template_default/common/tpl_main_page.php on line 119

I have tried everything and can not figure out what has happened. It was like a magica little fairy crawled in during teh night and screwed it all up



Thanks for any help you can offer.