It wasn't Communism or Socialism that collapsed, it was Sovietism.
Communism as a means of where workers own the firm and means of production hasn't failed. Look at manufacturing and worker coops. Some succeed, some fail. I'm guessing around the same rate that private and publicly owned firms do. Given that though, I'm willing to say that the idea isn't a failure.
John Green said it best. "Truth resists simplicity."
If you have a system where worker owned firms are exchanging goods and services on an open market using currency and capital as means of trade, is that a communist or capitalist society? What about when state governments establish rules that govern trade?
I'm a descriptivist when it comes to language. However, when the use of language is twisted as a way to paint people and ideas as "other" I have a massive problem with it. Don't get me wrong. I do understand that when we talk about "Capitalism" we're talking about western style capitalism where production and markets are more or less handled privately(Government regulations not withstanding). Conversely and by "Communism" we're talking about Soviet style communism where the state controls the means and focus of production. It's been a few years since I've read Marx and Engels, but I don't think this was the point of the mid 19th century communist movement.
So it becomes important to remember when we talk about things like Communism and Capitalism, things are pretty complex when you start to get serious into the terminology.
Did communism fail? Probably not. Has capitalism failed? Probably not either. It's likely that these are mutually exclusive ideas that can coexist.
Furthermore, how a state governs itself and interacts with it's markets complicate things further.
One thing i'm willing to bet on being pretty simple is that state planned production systems probably won't work. Not unless you got really lucky and the Government wasn't corrupt and somehow manages to provide for everyone.