Can't save page

For me it’s not possible anymore to save my page when I made some changes.
I deactivated all the plug-ins. But I was still not possible to save the page.
What else can it be?

Further it’s not possible anymore to upload new images. Than Worspress says: No temporary folder available.

And it’s not possible to display youtube videos anymore.

But i still like the theme. So i like to fix it!
Can you help me?

Thanks in advance!

Ow, and… when I want to save my page. The page jumps to the general page with all the posts… How strange is that?

Hello Kruimel,

You can try to reinstall everything (WordPress, theme, plugins) after creating a full site backup.

Please remember about importance of regular full site backups (files and database):
https://codex.wordpress.org/WordPress_Backups

Also you might want to check this tutorial:

Kind Regards, Roman.