Instead of moaning on you failure, try to analyze the true cause of your failure, in that manner, you will able to know that what mistake you made and why it happened? So in next attempt you will certainly not repeat the mistake! There is no other way to improve your mistake and harness success.

This is the reason that convince me that failure is the real buster of success.

Take the case of so many renowned scientists, political figures across the world. They did not blame others for their failure, infact they never moaned for their failure but taken their failure in their stride and keep on improving themselves, and the result is in front of us that still after decades and centuries we have to remember them, respect them as real genius.
So there is not a single man in the world who did not tasted failure. Just take example of a child, just observe it when it try to stand up first time in its life, observe that how many time it falls and after how many efforts it become successful in standing on its own feet!

Similarly look at Gandhiji, he did not succeed in removing British rule from India in single attempt! He kept up his movement, he analyzed his failure, learnt from it and keep up improving his struggle. And here we are! A liberated sovereign nation called India.

If Gandhiji would have thought that his movement with non-violence theory is wrong and meaning less, today he would not be the sole figure of non-violence in the world and so many political figurs and comman citizons across the globe would not taken him as a role model!
Hence it is totally up to us, how we look at the two sided coin, if you need a coin you will have to accept both the side of coin, you can not expect only one side, stop looking the failure as the split side of success, but acknowledge that with success and failure together one coin exist, I simply call it life!