lost most recent posts after upgrading WP

I have lost all 2011 and 2012 posts after upgrades. Went to Twenty Eleven theme, changed permalinks to default, tried use google library plugin, so not sure why my most recent posts are missing.

Example of my most recent post that is gone: http://www.exploreafrica.net/blog/2012/06/

Get internal server error!

Please help.
Cathryn