MMM, An investment scheme that has been in trouble around the world appears to have collapsed in Nigeria. The MMM scheme has seen its founder, Sergey Mavrodi, jailed in Russia in the past, but is still operating in many countries:

In the scheme invested money receives a return of 30% profit after a month. It works as a classic Ponzi scheme, where the incoming money from new members is used to pay members whose investment is withdrawn. These schemes work while they gain in popularity, but stop working as soon as they stop growing. The most famous example of this is the Bernie Madoff fraud, where it's estimated that $65 billion was lost.

In this case, the scheme appears to have reached the point where there is not enough money to pay the people who are trying to withdraw their funds, and so the accounts have been frozen. I assume that nobody currently in the scheme is going to see their money.

As always with these schemes, if it sounds too good to be true it probably is. Also, even if you manage to make a profit from one of these schemes by joining early enough, that profit is made at the expense of others further down the chain who are being ripped off by you.