NullReferenceException Please Help!!

Hello Im new in unity and I have a problem, Im making a collab with a friend and I had the game working but then It suddenly gave me this error and even though I try to restore my previous game, it seems that it still doesnt work. So Ive looked all over the internet and I cant find why this is wrong.
I have my class GokuHealth, and my class HealthBar, In GokuHealth script theres a public HealthBar called "gokuBar", since HealthBar is Mono:Behaviour You have to instance it through unity (I think so), and I have done that, never the less it stills throws me this "NullReferenceException: Object Reference not set to an instance of an Object"
There's something that I dont understand also, that like you can see on the images that I uploaded, in GokuHealth script on the GetkeyDown, O and P (THE ORANGE ARROWS on the img), the console throws me an NullReferenceExeception error, but it stills works the gokus healthbar in the game goes up and down and it prints the value of its health.
Nevertheless on the method on trigger2D it prints "DAÑO" in the console, but it fails to do the rest.
Please help <3 and sorry for bad english

 

It would take too long to figure out where the error is by going through all of your scripts.
Instead, post the exact error message. It will show which line in which script the error is occurring.

 

It is posted, in INSTANCE img there's the console, with all the problems, I think the main one relies on this
NullReferenceException: Object reference not set to an instance of an object
GokuHealth.Start () (at Assets/Goku/Scripts/GokuHealth.cs:9)
that image has 0 views lol

 

You should probably rename the GokuHealth Start method to Awake. I don't have time to test what I'm saying, but I think this is an initialization issue. So it's just a tip.

 

Tried it, throws the same error.
NullReferenceException: Object reference not set to an instance of an object
GokuHealth.Awake () (at Assets/Goku/Scripts/GokuHealth.cs:9)

 

Well, then I have no idea without build your entire code and go through step by step and insert debug log around the problem. Which you can do easily.