Categories Gone

Hi!

I have a large problem, my categories is gone. I use WP-dTree widget, it’s has worked really fine intill today. I have alot of categories, but I can’t use the standard widget for categories becouse then it will not format that in the correct way. I know I changed some of the categories last day, like putting a couple of categories within another parent, rename a couple etc. but I have done this alot of times, but suddendly now my categories won’t work. what can I do?

the address is https://www.sixcast.com