Confession:
I've been working as C# programmer for an entire year, and I wrote desktop app as well as win services, but when it comes to practice (cause I moved to PHP about 7 months ago) on Codewars I go completely wrong, and it's even worst on Hackerrank.
Have to admit, feel so dumb and lost

Hello there,
There is absolutely no reason for you to feel bad.
Competitive programming is different than working in a real project and building things.
Stick with code wars or hackerrank and you will get in that "mode" in no time.

I am a blue (level 4) on Code Wars but I have not done things like writing complete desktop apps yet. :/

Thanks dude! Feel less alone!