You didn't get German citizenship automatically, but you want to become German?
Naturalization almost always requires living in Germany. Naturalization from abroad is only possible in a few exceptional cases, about which you can find information here.
Naturalization as reparation
Between 1933 and 1945, many German emigrants were deprived of citizenship for political, racial or religious reasons. Since the Federal Republic of Germany was founded, those affected and their descendants can regain citizenship in accordance with Article 116 (2) of the Basic Law. You can find information here.
Naturalization of former Germans
Did you lose German citizenship because you acquired a foreign nationality on application and did not have a retention permit?
When did you acquire the foreign citizenship:
Essentially, the following applied: Anyone who, as a German abroad, acquired foreign citizenship on application and did not have a retention permit lost German citizenship in accordance with Section 25 of the German Citizenship Act. Under certain conditions, there is the possibility of naturalization. Naturalization generally requires permanent residence in Germany. Naturalization from abroad is at the discretion of the Federal Office of Administration and is only granted in exceptional cases. The conditions for naturalization of people not living in Germany are particularly high, there must be a public interest in naturalization.
Anyone who acquired a foreign citizenship upon request and did not have a retention permit lost German citizenship in accordance with Section 25 of the Citizenship Act (StAG). There is the possibility of naturalization according to § 13 StAG. The prerequisite is that if the application was made in good time, a retention permit would have been granted and the necessary ties to Germany still exist today.
Since an amendment to the Citizenship Act that came into force on August 28, 2007, a German citizen no longer loses his German citizenship if he acquires the citizenship of an EU member state or Switzerland after that date. In this constellation, an application for the granting of a retention permit is therefore no longer necessary and German citizenship can be retained automatically.
However, old cases are not affected by this regulation. If the application was acquired before August 28, 2007 without a valid retention permit, the automatic loss of German citizenship in accordance with Section 25 StAG continues to exist. Under certain circumstances, however, an application for reinstatement can be made.
Naturalization of marital children (former) German mothers and their descendants
Did you not acquire German citizenship by birth because you were born before 01.01.1975, only your mother was German and you failed to make a declaration between 01.04.1953 and 31.12.1974? Or are you a legitimate child of a German mother who, prior to her birth, had lost German citizenship by marrying a foreign man under the previous rules of German law?
Then naturalization according to § 14 Citizenship Act is possible for you and your descendants under certain conditions. Among other things, you have to prove that you have a close connection to Germany and speak German. You can find more information here (in German).
Naturalization of illegitimate children of German fathers and their descendants
Did you not acquire German citizenship by birth because you were born out of wedlock before 01.07.1993 and only your father was German? And the prerequisites for citizenship through legitimation weren't there either?
Then naturalization in accordance with Section 14 of the Citizenship Act is possible for you and your descendants under certain conditions. One of the prerequisites is that you have close ties to Germany and speak German. You can find more information here (in German).