Where to start when looking for a parent without any info?

Your own mother doesn't know?

What does it say on your birth certificate?

Are you the product of a rape? An affair? A relationship? A one-night stand? The answer to these questions will give you an idea of how successful you might be. If you are the result of your mother being raped by a stranger, and there was no arrest and no prosecution, then your chances of finding your biological father are vanishingly small. If you are a child born of a long-term relationship, then someone surely saw your mother with that man (e. g. a grandparent, a sibling, a classmate, a cousin, a coworker, a neighbor, etc.).

If you've got some $$, you might want to get a full DNA workup. They aren't perfect but you might get a handle on at least the race of your father, and possibly some hints on his ethnicity, particularly if your mother or any siblings or half-siblings get a similar workup.

What is your description? Do you know your father or are you just making yourself find-able?