So your “A” plan didn’t work out, do you immediately go into your “B” plan?
I say not, you first need to dissect your “A” plan again get some understanding of what worked and ultimately what didn’t work. You see the idea had some level of merit or you wouldn’t have went forward with it. Was it your execution, the market, competition or just a poor idea? Even poor ideas have some level of worth in them.
Even the worst ideas can help you with key learnings about your pursuit, your skills or your perseverance.
So in the breaking down or breaking apart your “A” plan into small bite size pieces, you will learn many things about yourself.
Should you have zigged instead of zagged?
Should you have been more aggressive?
Should you have stopped it earlier?
Should you have gone faster?
Slower?
There are many things you can learn with the perfect information looking back can offer you.
After all it happened, so you now know the idea the way you did it doesn’t work.
Check off your first key learning. Second, you will have learned what you wouldn’t do again: Boom Second (maybe third and fourth) key learning.
You get the point, you need to inspect what you expected and figure out honestly, why you got the result you did before moving on to your “B” plan.
Your “B” plan will be that much better with the honest acceptance of your key learnings from a failed “A” plan. By the way, here’s a clue if your “B” plan doesn’t work also. Go back and review and figure out your key learnings from your “B” plan, then combine with your key learnings from failed “A” plan and start your “C” plan.
Remember the key is to learn but not stop, as there are many letters left in the alphabet.
Your “B” plan will be that much better with the honest acceptance of your key learnings from a failed “A” plan. By the way, here’s a clue if your “B” plan doesn’t work also. Go back and review and figure out your key learnings from your “B” plan, then combine with your key learnings from failed “A” plan and start your “C” plan. 
