Problem solved – everything looks good again. Japanes, Ivrit, Spanish, German, French, Turkish …
And just in case somebody has the same problem: I learnd that the problem was caused through an update from PHP Version 5.4 to 5.6. And that it was necessary to fill in the following code:
// define(’DB_CHARSET’, ’latin’);
This brought all the ü, ?, ? etc. back again ??