My father suddenly withdrew his consent a few weeks before the marriage contract (akad nikah). What can we do?

Find out the reason for the change first; if his reason is not reasonable in terms of Islamic law, the Syariah Court can consider an application for a wali hakim. Perhaps your father heard something about your husband-to-be, or there is a misunderstanding between the two families. Ask for a calm face-to-face meeting with a go-between respected by both sides. If his concern is well founded, for example about the man's religion or character, take it seriously. If not, discuss the next steps with an officer at the state Islamic religious affairs office. Hold back any unpaid payments for the ceremony until things are clear. See a wali who refuses to marry off.