In abstract, questions about Nikkah are perfectly fine as far as I can tell. What isn't so fine on our religion sites is asking for "personal guidance in response to practical questions". On this site these questions have been labeled (Islamic) counseling and agony-aunt.
In this particular case, the question doesn't have nearly enough detail to be able to responsibly answer. The three things the OP told us are:
- She's 17.
- She's in need of Nikkah.
- Her parents won't let her.
I don't know much about the topic of Islamic marriages, but reading the Wikipedia page convinces me that many, many more things must be known about the OP's situation in order to provide useful help. At the very least, we'd need to know why here father has rejected the marriage since "the contract of an Islamic marriage is concluded between the guardian (wali) of the bride and bridegroom, not between bridegroom and bride." (According to Wikipedia.) I suspect that even a mullah who knows her family well would have a difficult time answering wisely. Why would we, who know so very little about her, agree to give her advice?
Perhaps just as importantly, a question on Islam.SE should be "one for the ages". That is to say, if the question could be rephrased to be helpful to all sorts of people in the future, it will be much more useful. Asked in the abstract, the question might be useful and interesting; in this specific instance, leaving it open is taking a gamble.