cart shows only text no html

I have had OC running very well for several years, but yesterday instead of the normal front page I got a text version that looks like a directory down the left hand side of the page. I have looked at the index.php and nothing appears to have changed. I suspect that something in a file has been corrupted, but have no idea where to look. Any advice would be appreciated.
Thank you
Trevor

This is a discussion board, not a support board. Please post your question here:

http://forum.opencart.com/viewforum.php?f=180

for support.