Too much is the point where you are not aroused or when your masturbation is causing damage to your penis. There is nothing even close to a normal time for ejaculation. Nothing about the penis is normal, it is one of the most unique facets of a man.

what will happen if i over masterbate . i trie it ,and not i couldnt get hard .. i am really stressed .whats happening with me .. plz help.

If you're not properly lubricated you could damage the skin or nervous tissue from friction or rough handling. Severe issues could cause scarring and loss of sensitivity.

What do you mean you "trie it"?