Please help: Theme design does not show anymore

Hello all,

I would really appreciate a quick help!!! I don't know how it happend, but my Blog front-end is not showing the theme design anymore:

http://www.reisen-mit-rucksack.de

I was changing plain text content in my text widget in the sidebar and after I saved it my blog looked like this. I have deleted the widget now but still it won't change back to the correct theme display.

Does anybody have any idea how to fix this?

Thank you very much!

Ineu