problem with the admin of the site

Hi
I have a few problems with the admin of my site.

1- Last night all the pages disapeer and return 404 – but they come back after few hours.

2- Know: when I try to publish a post I am not able to put the post in category, because I do not see any.
when I try to publish a post I am not able to publish it, I can only "serve it to confermatian"
I tried to turn of all the plugins delete the cach and start again the computer but it did not work.

I am using wordpress 3.7.1.

Last thing I do is to update yoast seo.

Before that I add the plugin VaultPress, it works well about 4 days. Know it turns of.

And I want to ask about your live chat – when I am going to the chat page I see times and people that are expert in some field, but I do not see any chat box.
how can I use your chat?

Thank you