If you are married or in a registered civil partnership but living separately, you can demand reasonable maintenance from your partner even before the divorce.
If you are legally divorced and you are unable to support yourself, you can claim reasonable maintenance from your former spouse.
If you want to end your civil partnership, you can apply to dissolve your civil partnership.
Here you can get information about divorce.
If you have lost your divorce decree or divorce order (divorce certificate), you can apply for a new certified copy or duplicate at the local or family court where your divorce...
If your marriage was divorced outside Germany, you can have this decision formally recognized in Germany.