Recovering confidence after a fall One month has passed since I fell on a mountain bike trip. The accident wasn't critical, it just left a huge scratch. The accident happened during a fast descent when my front tire hit a little crack.

My problem is that I don't feel confident riding descents anymore. My mind gets afraid and it impacts my riding. What should I do?
Keep riding.
It will take a little while to come back, but it will come back. Just don't push yourself too hard, as you will be tense and stiff and those things can lead to another accident. For all practical purposes your skill limit has decreased, so riding at your old limit is riding beyond your limit until you get past the mental block caused by the crash.
Try to analyze what happened in the crash and learn from it. Were you riding too fast for the trail or your skill level? Did you pick a bad line? Did you use your front brake at the wrong time? Replay it in slow motion in your head. Pick it apart and learn from the mistake. If you can find what the limiting factor was that caused the crash you can become a better rider because of it.
Once again, just take your time and ease your way back into riding at the level you were at prior to the crash. Eventually the fear will dissipate, and if you've learned from the incident you will be a more skillful rider than you were before.