Can a Revert to Islam Change Their Last Name if It Is Not Their Father's?

Walekumussalam,

Your accepting Islam is a great blessing may Allah grant you steadfastness.

The answer to your question is that, in Islam, the basic rule is that a person should be attributed to their real father. However, your situation is different  your current surname is not your father’s name, and you also do not know or have any way to contact your real father. In such a case, you are not required to keep a wrong attribution.

Therefore, it is permissible and even better for you to change your last name, as long as you do not link yourself to someone who is not actually your father. You may choose a neutral or general name that does not falsely claim a father’s identity.

However, it is not allowed to knowingly attribute yourself to someone who is not your real father.