How can I solve this?

Yesterday I got a D3D11 swapchain error (while importing an asset). Since then, build settings stopped working, and if I try to open popups like aspect ratio, it throws me this error:

NullReferenceException: Object reference not set to an instance of an object UnityEditor.EditorWindow.Close () (at :0) UnityEditor.PopupWindow.CloseWindow () (at :0) UnityEditor.AssemblyReloadEvents.OnBeforeAssemblyReload () (at :0)

Project settings, gizmos settings, preferences works perfectly.
I tried to reinstall Unity, open the project in several other editor versions, reinstall unity hub too, and (obviously) rebooting, but nothing works. Please help me!
PS: Sorry for my bad english, I'm Hungarian.