How can a 19 year old turn 55k into 100k before 21?

Any option which has the potential to make that return in that short of time has just as much risk (probably more) of you losing most of your money.  That said, I don't know of any legit investments with that type of return.  Your only real path would be gambling (cards, sports, etc.)

Instead of awarding D.E.B.S. Favorite Answer, call a financial adviser and get the truth. Listen to the Ric Edelman Show. You can also email him. Please find the link below for his online show. Please don’t waste your money on gambling. 

Doubling your money suggests an annual rate of 40% for two years.  If you could do this, you should be managing other people's money for a fee.

Highly unlikely that you'd double your money in 2 years. Anything with that high a potential return is also very risky. There's no guarantee that you would achieve that return, and with something that risky there is also the potential that you would lose money.

You may get a better (and more rapid) response if you post this question in the "Investing" section.