What to do if my dad invested the money I inherited in a pyramid scheme?

I inherited $12,000 from my grandmother when she died, and my dad was the trustee until I was 18. He invested it into the stock market, but when they crashed in 2008, he took it out. He then "invested" it in some stupid online business pyramid scheme type of thing and now it is all gone. He said that it was an investment, and he thought it would work, but now I don't have any money and I would be getting $12,000 this October when I turn 18. My little brother and sister's $12,000 inheritance each was also "invested" into this pyramid scheme thing. My dad just has no business sense. I told him not to do it, but I couldn't make any decisions for him since he was the trustee of the money. Now I really need it to pay for college like my grandmother intended, but it's gone. What can I do?/?????