What are the steps that a virgin or previously married woman can take if a Wali (guardian) is abusing his authority and refuses to marry his daughter to a suitor?

If her Wali prevents her from marrying a suitor for no valid reason according to Islamic law, then the role of the Wali passes to the next closest relative, so it passes from the father to the paternal grandfather or uncle, for example.

If all of her paternal male relatives prevent her from getting married for no valid reason according to Islamic law, then the ruler is her Wali, because of the hadith:
(“…If they dispute, then the ruler is the guardian of the one who has no guardian”)

If there is no Wali and no ruler, then she should appoint a trustworthy Muslim man to arrange her marriage.