You shouldn't feel a failure at all, and at 26, you've got soooooooo much life ahead of you yet! I know what it's like to go through what you're going through. I had very similar circumstances to what you've described. That was when I was 32. I thought that I was a total failure, and would never amount to anything. I came across an opportunity in a field totally unrelated to what I went to school for, and I never looked back!

Having a short term bad run of things going wrong seems like wasted time and that things will never improve. I'm a firm believer in things working out how they're supposed to work out. It sounds like you've hit a reflection point, and that you're doing a great job of learning from things. It sounds to me like you're going to do very well for yourself. Don't let the short term get you down!