all of a sudden everything is broken

I was working on my 4th level when I got a glitch where I couldn't drag stuff from the hierarchy or project browser
(everything was working fine and I could play my project without any problems) so I was advised to restart my computer but when I got back onto unity there were millions of errors in the console and I couldn't play the game I will give a list of all the errors: there is lots of the first one
Non-convex MeshCollider with non-kinematic Rigidbody is no longer supported in Unity 5.
If you want to use a non-convex mesh either make the Rigidbody kinematic or remove the Rigidbody component. Scene hierarchy path "cratestack 5", Mesh asset path "" Mesh name "Plane"

UnassignedReferenceException: The variable Cam of Aim_sight has not been assigned.
You probably need to assign the Cam variable of the Aim_sight script in the inspector.
Aim_sight.Update () (at Assets/Tutorial 5/Tutorial 5/Aim_sight.js:7)

The 'InvPauseGame' script on Inventory has a variable called 'disableMouseLookComponent' which is set to true though no MouseLook component can be found under (either) the Player or Camera
UnityEngine.Debug:LogError(Object)
InvPauseGame:Awake() (at Assets/Inventory/Scripts/Other/InvPauseGame.js:45)

There is something in front of the object!
UnityEngine.MonoBehaviourrint(Object)
gunstuffs:Update() (at Assets/gunstuffs.js:20)

There are 2 audio listeners in the scene. Please ensure there is always exactly one audio listener in the scene.


btw all of this wasn't happening before I restarted and now my game doesn't work