It's clear that you're having a hard time with this one. Unfortunately these things do happen sometimes... I completely empathize, recently having had some trouble with some hands-on things which I nailed before.

Sometimes we have bad days, and it's good to just step back, cool off, and reassess what went wrong from a less-stressed mindset.

Take it easy for a bit and come back later. Sometimes the new perspective will show you something you've missed. In the meantime, it'll bring your head back into its rightful space, and you'll feel happier.

Remember that you'll get this. Just make sure you take the right steps to get there, and that includes resting. I believe in you.