No graphics on website

,

I have redinstalled the owncloud 10.11. Well it seems it works, but I do not see any graphics on the intro page, there is also no graphic interface after logon. I see only text:

owncloud_bad

I really do not know what has happened. I tried to reinstall, change the owncloud installation catalog, change the database. Nothing has changed.

Any advices ?
Kacper