Dad has forbidden me to wear niqab.I've been told that it's haram to disobey him. I strongly believe that the niqab is wajib. So I'm wondering what approach I should take to this dilemna?

It is very heart-warming to see the strong determination you have to observe Hijab and to protect your chastity. Obedience to your parents is necessary as long as it does not entail contravening any of the commands of Shariah.

In this case, as he is preventing you from something Fard, it would not be permissible for you to obey him in this matter. It would still be necessary for you to respect and honour him, however don't allow him to stop you from observing hijab. Make dua to Allah to open the Haq to him and try your best to explain to him the importance of hijab.

and Allah Ta'ala Knows Best

Mufti Ebrahim Desai