HDRI sky disappeeared and is now all objects are invisible and scene is gray?

Recently, I was trying add a script component to a UI button. I wasn’t seeing any of my scripts on the list an accidentally clicked on “Scene Render Pipeline”. After that, now my objects on the scene are invisible. My scene had that default bluish color scene with lighting. Now every thing is gray I can click on the objects but cant see anything. How can I fix this? i got an error message saying NullReferenceException: Object reference not set to an instance of an object NullReferenceException: Object reference not set to an instance of an object
UnityEditor.Rendering.HighDefinition.HDRISkyEditor.OnEnable () (at … Please Help.

Had the same issue, but with URP. It seems like Scene Render Pipeline script clears Scriptable Render Pipeline Settings field in Graphics settings, so I just reassigned my URP asset there and it fixed everything.