Sudden You do not have sufficient permissions to access this page in wp-admin

Sudden You do not have sufficient permissions to access this page in wp-admin

In my case, I just change browser and it will work i use firefox and it works for me. but this situation can arise due to many faults.

Try to just rename plugins folder to plugin1 and try to login to admin panel.

If this not work , try to give permission to wp-admin to 777.

OR TRY THIS

I commented out lines 89-91 in wp-settings.php and my problem was solved. Like so:

// Append the query string if it exists and isn't null
/*if (isset($_SERVER['QUERY_STRING']) && !empty($_SERVER['QUERY_STRING'])) {
	$_SERVER['REQUEST_URI'] .= '?' . $_SERVER['QUERY_STRING'];
}*/