Has socialism already been tried and failed?

I would say that the USSR was not socialism, but state capitalism.

What occured in the USSR was not pure socialism. While the original ideal was to bring about a socialist utopia, what was actually created was Stalinism. So yes, socialism did fail in the USSR, but as Karl Marx would readily point out, they were not in the right stage of social evolution for such a revolution to take place. According to Marxist theory society must pass through a stage of Capitalism, which under the weight of its own hipocrasy would devour itself, allowing a socialist revolution. So you can also state that socialism has failed in reality, but that does not mean it cannot succeed.

It works, I believe, just capitalism works because the nature greediness of human, and socialism works the opposite site, the williness of sharing of human nature. But if compare this 2, capitalism works easier,one of the reason I think is is more difficult to persue one individual to share then to keep things for his/her own. Socialism will work untill everyone understand infact socialism can lead our human civilization brighter and faster, instead that socialism has been giving a imej that everyone will live in poor, why not everyone live with great fortune, all the things can be done so effectively and so easily if human do sharing. But just im not sure this mind of state will come reality.So the point is how human behave.