I flew a leg straight on the balkans challenge without follwing the way points. After landing nothing happened. I went back one leg to fly it all over again and still stuck on that airport and wont validate the landing.
How can I reset this?
same thing happened to me in the Balkans, twice.
Once I was off the runway. The other I landed in the opposite heading it was expecting me to. So I took off, went around the airport and landed the other way. Leg completed 
Bush Trip, Breckenridge to Mariposa - Palomino NV47
Me too, it is a confusion of airstrips and airstrip lookalikes! There are 2 locations with runway numbers on, the first I tried landing and was dodging traffic, the second is a glider airfield. I then checked in my Aviation Tools app and got the coordinates and put those into Google Earth and surprise - it was exactly where it showed on FS2020 for NV47.
I am sure there must be some real life iffy landings around there!
Updated Breckenridge to Mariposa Bush Run Flight Plan via Google Earth.
https://earth.google.com/earth/d/1Uip9719SX1StRJAYwf47wyQLrA8fWNzf?usp=sharing
Check this out for NV47. I did this leg 5 times. It’s the one with the green plane…
h t t p s://ourairports.com/big-map.html?airport=NV47