Sorry to hear that. Here is a little tutorial on how to proceed, and if that doesn't solve the problem, I will try to find a way to resolve what's causing the issue.
You can try to double jump,
or do a simple jump,
or slide and then jump.
After doing that, you still need to press the W key or the up arrow.
In this part, you need to jump and then climb the wall.
Again I'm sorry, the game is not entirely polished. If this is not where you got trapped, you can tell me, and I'll help you figure it out. I'll correct the bugs as soon as possible. Thank you for the feedback :D