Problem with wordpress dashboard

Try deactivating all plugins. If that resolves the issue, reactivate each one individually until you find the cause.

If that does not resolve the issue, try switching to the Twenty Sixteen theme to rule-out a theme-specific issue (theme functions can interfere like plugins).

If those don’t work, add define('CONCATENATE_SCRIPTS', false); to your wp-config.php file just below the define('DB_HOST' line.

To do so, access your server via FTP or SFTP and edit the file with a plain text editor.

https://codex.wordpress.org/Editing_wp-config.php#Disable_Javascript_Concatenation