WP 3.8.1 upgrade failure

I just upgraded to version WP 3.8.1 (from 3.8) using the link in the Admin UI to do so. Now although I can get to the admin dashboard (by typing the direct URL into my browser) I cannot load my site home page. All that shows is the header image used in my theme (Twenty-ten). No menus – nothing, just white space underneath that image. I’ve tried rolling back to WP 3.8 (that is, installing 3.8 over the top of 3.8.1.) but this error persists. Any help/suggestions/comments much appreciated.

Edit: Forget it. Faulty plug-in update I did just before the upgrade, Sorry for the alarm bells!