Geometry Dash won't open
Solution 1:
I'm not an expert, but this worked for me when I encountered this bug so I hope it helps.
Press WIN+R and type appdata, then click Local. Go the the Geometry Dash folder, and delete CCGameManager, CCGameManager2, CCLocalLevels, and CCLocalLevels2.
When you open your game, it will reset some stuff like songs and levels. But once you log into your account, it should work fine.