How should I invest $1000 once for about 3 years at med/high risk for high gain?

[?]

I don't need regular yields/dividends because I want my earnings to get reinvested.

[Aazoba]

try buying 1 contract of Boieng (BA) jan 2016 $165 call ..if it hits that price, you'll make thousands in less than 2 years

[Chris]

consider foreign markets. economies with high growth rates will increase the value of your investment. The WSJ yesterday talks about the mass number of IPO expected to take place in 2014 in China. If you believe in the secor and company, getting in on an IPO has the potential to make you a lot of money! for example twitter - on day of IPO share price rose 73%. However dont expect these massive returns jus because there is an IPO!!

Just thought i'd give you something to look into!!

as aazoba menioned, call options are nice too! just make sure you know how they work before you purchase them...