Try manually resetting your plugins (no Dashboard access required). If that resolves the issue, reactivate each one individually until you find the cause.
If that does not resolve the issue, access your server via FTP or SFTP, navigate to /wp-content/themes/ and rename the directory of your currently active theme. This will force the default theme to activate and hopefully rule-out a theme-specific issue (theme functions can interfere like plugins).
Yeah , i find the problem 🙂 and i solved it , but ihave another problem
THE WHITE SCREEN OF DEATH , how to solve this problem , i realy do anything but it not solved !
WORDPRESS 4.2.4
Try the above steps again.
If that doesn’t fix it, try downloading WordPress again and delete then replace your copies of everything except the wp-config.php file and the /wp-content/ directory with fresh copies from the download. This will effectively replace all of your core files without damaging your content and settings. Some uploaders tend to be unreliable when overwriting files, so don’t forget to delete the original files before replacing them.