How to use "Never"
She never sleeps
She never slept
I never live
I never lived
He never loves me
He never loved me
This is never happen
This is never happens
This is never happened

What are the meanings and the differences beetween those?

Question

How to use "Never"
She never sleeps
She never slept
I never live
I never lived 
He never loves me
He never loved me
This is never happen
This is never happens
This is never happened

What are the meanings and the differences beetween those?

Answer

She never sleeps.(correct, simple present)
She never sleep.(wrong, she never follows v1)
She never slept.(correct, simple past)

I never live. (correct, simple present)
I never lived.(correct, simple past)

He never loves.(correct, simple present)
He never love. (wrong, he never follows v1)
He never loved me.(correct, simple past)

Never happen/happened.(both are correct)

He/she/it/any name are followed by verb form5(v5).
I/we/you/they are followed by verb form1(v1).

sleep(v1) slept(v2) slept(v3) sleeping(v4) sleeps(v5)