All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and Messenger.
First of all, we ask Allaah to make a way out to your difficulty and bless you with a good husband.
The characteristics that should be considered when looking for a suitable man for marriage are religion and good moral conduct. Therefore, if this man is pious, your father should not refuse to marry you off to him, and it is suitable to try to convince your father to accept to marry you off to him.
If you are embarrassed to talk to your father about this matter, then you may seek the help of your relatives who may influence him –including the female relatives –like your aunts and the like. You should continue in trying to convince him until you are predominantly sure that he will not change his mind. For more benefit, please refer to Fatwa 87295.
You should know that having complete trust in Allaah, does not mean that we should not utilize all permissible means. Moreover, we do not know any supplication for having self-confidence. Hence, you may supplicate with general supplications, like the supplication of the Prophet, sallallaahu ‘alayhi wa sallam: "Allaahumma rahmataka arjo fala takilni ila nafsi tarfata 'ayn, wa aslih li sha'ni kullahu, la ilaaha illa ant."
"O Allaah, it is Your Mercy that I hope for, so do not leave me in charge of my affairs even for a blink of an eye and rectify for me all of my affairs. None has the right to be worshipped except You." [Abu Daawood]
For more benefit, please refer to Fatwa 85447.
Furthermore, you should know that it is permissible for a woman to look for a pious man to marry her provided that this is done within the good moral Islamic conducts.
If your father prevents you from marrying a suitable and competent man, then you may take your matter to an Islamic court or to any institution that studies the personal matters of Muslims, like the Islamic centres, if you live in a non-Muslim country, so that they will look into your matter. Then, if it is confirmed with the judge that your father is preventing you from marrying without any valid reason, the judge will marry you off or appoint someone to marry you off to a suitable and competent man.
For more benefit, please refer to Fatwa 83394.