My unity 3D screen went black and i dont know what to do

my screen is black i looked it up everywhere but nothing helped please help!

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Restart unity when it goes black.

I had this same problem whilst following one of the beginner tutorials, what worked for me was the following:

Edit/Preferences/GI Cache, then click ‘Clean Cache’. Unity will then rebuild the Light Mapping.

Just make another scene and then again go back to your default scene , it will automatically rebuild .