What happen when you fail NoFap

Whether or not you will lose everything depends on you. The best you get out of relapses can be an experience to learn from. What let you to relapse, what did you do to stop it, did you try to stop it, how hard did you try ? What will you do next time to prevent it, how will you deal with urges etc.
All of these can serve as a lesson, it doesn't have to mean its a complete loss. That just depends on you, how will you take your relapse ? Will you take it as a defeat or a lesson ?

How many days you need for benefits cannot be precisely determined, but it is very certain to say if you binge on porn it'll take more time to recover. Also, im not an expert but i think there's no way you can run out of testosterone, your body is constantly producing the hormone

Basically, dust yourself off and everything will be okay. Just stay persistent and wise about it and wonders would happen