Hello,
I tried these three
– deactivating all plugins to see if this resolves the problem. If this works, re-activate the plugins one by one until you find the problematic plugin(s).
– switching to the Twenty Eleven theme to rule out any theme-specific problems.
– resetting the plugins folder by FTP or PhpMyAdmin. Sometimes, an apparently inactive plugin can still cause problems.
Which didn’t resolve my problem.
I am going to try now
– re-uploading the wp-admin and wp-includes folders from a fresh download of WordPress.