Pages not found

Can someone help me?

I’m using the plugin Qtranslate. The static page didn’t work as I wanted, because it didn’t show the other languages. I tried to delete the page, made a new one and set it as static page. What happened next is that only the static page works and all other pages are ‘gone’. When you click on ‘contact’ for example, you get a page with ‘oops, a little embarrassing isn’t it? We couldn’t find the page blablabla.

Does anyone know how I can fix this problem?
The website is arnowestenberg.com

Thanks in advance!