I would not concede your money to your dad IF he is really wronging you - and we need much more detail to tell. This is the first lesson in life that actually following up on "wrong" things will save you thousands of dollars throughout your adulthood. It is really easy to turn the other way and be out a few thousand dollars. Then the hospital overbills you and you let it go and so on. Follow up, it is your money.
The laws behind this are pretty cut and dry. Basically if you put money into one account and only your money was touching the account then it is your money. As a minor this is an expectation and once your turn 18 in the US you have a right to your money. That is given that the money was in the account at 18.
So if your dad truly did not touch the account and withdraw the money before you turned 18, it is cut and dry. If your dad took money out before 18 or added his own money to the account it gets rather fuzzy since it is easy for dad to say that I took money out for your expenses.
As for this being "nuclear" as keshlam suggests - he is right. His advice is fine but sets you up for people taking advantage of your throughout your life, especially your family. In fact the situation is already nuclear but you were the only thing the bomb hit.
So talk to your dad. Explain that you will have to go and file a small claims trial if he does not agree to give you the money. If your situation is already over the top I would bring the paperwork with you filled out. (a person at your local clerk's office will help you find the right forms)
You on the other hand better weigh this conversation. We "internet peoples" are only hearing one side of the story. We do not understand your situation at your home. We don't understand who pays for your car, gas, clothes, and room and board. You are 18, so there is no obligation for parents to pay for these things.
If I had an 18 year old that had 3K in the bank under my name and they hadn't helped around the house in a year, didn't buy their car, had a poor attitude, and so on I would probably have the same action as your dad. Yea it's "your money" but is it really? When I was 18 I bought ALL my clothes, bought my car, bought my gas/insurance, and so on. I paid for my toothpaste. If this is where you are at and you help out around the house like an adult would then you have solid ground to stand on.
If not... I would laugh if I were your dad. My first thought would be you want your money, that is fine. But you are paying rent. Car is gone, get your own. You would be paying for everything. But you would have "your money". So you have some pros and cons to weigh here and taking the money could cost you a TON of money in the future. However if your dad is just being a pure jerk (I kind of doubt this but who knows) then you have an obligation to fight for what is yours.
(Note that the end goal of any meeting like this in your life shouldn't be court. It should be an agreement so that the right action is taken and both parties are happy. It could be very well that your dad would be happy with something that has nothing to do with the money. Also there are people with really really bad situations at their homes. A controlling parent is a pretty good "bad" situation and an easy one to solve at 18 - move out. If you don't want to move out then accept your family members, not complain about them. No matter how controlling your dad is your question spews of ungrateful teenager. I am sure you aren't that bad and I am sure your dad isn't that bad.)
(And another note: In no way, shape, or form am I suggesting you drop the money issue. There is nothing worse than not talking about it even if you think your dad will kick you out of the house. Resentment building up in yourself or family is the worst possible thing. This needs to be dealt with.)
