Use failures as an opportunity to learn. I have at least four _unambiguously failed_ projects under my belt, and every one of these taught me something important.

As explained in [this fantastic answer](http://workplace.stackexchange.com/a/1485/168),
> Judgement comes not from success, but from failures. Most companies want to hire people that have had their failures paid for by previous companies, that is why they require `N+ years of experience` it implies they made all the **basic, entry level mistakes** already and someone else had to pay for them.
> 
This judgement only comes with experience.
> 
Edison invented the light bulb through experiencing failure, not through some raw in-experienced skill...

Set up a project postmortem / retrospective. Study how it went, what was done right and what could have been done better.

Learn how to apply acquired experience to your next projects... oh wait, it is impossible to adequately cover in an answer such a topic without knowing specifics of your project. For a starting point, refer [Conducting a Project Postmortem](http://www.gamedev.net/page/resources/_/reference/105/169/296/conducting-a-project-postmortem-r977) article by Steve Pavlina:
> The best time to conduct a postmortem is about two weeks after a product is released (or for certain products, after the project is cancelled). This allows you to regain your objectivity without forgetting the details. Your memories will still be fresh, and you'll have a good perspective to see the project as a whole rather than focusing too strongly on the most recent work...