4. Use the Six Thinking Hats Technique
If you are stuck at some point & cannot see through, it is time you need to use SIX THINKING HATS technique. Forget all previous things & start with a blank page. For example, White hat, to look for what went wrong, green hat, to look at possible alternatives, black hat, to calculate all the loss, yellow hat, to look at the brighter side; and so on.