I can not see the Files part, and win client can not connet to server

Hi All,
I installed the latest version of ownCloud in my WP site and made some changes on template
(just changed logo, background color, favicon and main page footer)

yesterday everything was perfect, I was able to use win desktop client and already uploaded some files.
However, today desktop client disconnected and although I tried to login with server name username and pass.
it gives a warning like "There was an invalid response to an authenticated webdav request"

Additionally, when I login to server page, I can not see the Files part, whrn I click All Files screen is like this


does your log give you any clue what the error might be?

I think modification caused this problem but at first everything was OK
I do not know what I can do

Well, can you check the ownclod.log for errors?

Yes, but there is no remarkable thing within that. I will try to uninstall and reinstall, I suppose that there is no alternative solution