after I have deleted as you suggested the WebAssist folder and connection folder seems to work but when I change the design of the site and save I get this message:
Internal Server Error
The server encountered an internal error or misconfiguration and was unable to complete your request.
Please contact the server administrator, firstname.lastname@example.org and inform them of the time the error occurred, and anything you might have done that may have caused the error.
More information about this error may be available in the server error log.
and nothing changes.