Root directory issue

Recently, I changed my URL’s homepage from diabeticssupportsocks.com to
diabeticssupportsocks.com/2009/what-are-diabetic-support-socks (in my
admin.’s ‘General’ section under Settings) and as a result, it screwed up my
root directory.

This is what I’m getting when I log-in or click on –
diabeticssupportsocks.com/2009/what-are-diabetic-support-socks

Internal Server Error

The server encountered an internal error or misconfiguration and was unable
to complete your request.

Please contact the server administrator, support@supportwebsite.com and
inform them of the time the error occurred, and anything you might have done
that may have caused the error.