Its a bit complex: http://www.differencebetween.net/language/words-language/difference-between-never-and-ever/

'ever' means at any time 'never' means at no time The relationship between 'ever' and 'never' is like the relationship between 'anything' and 'nothing' or 'anybody' and 'nobody'. For example: Have you ever been to London? = at any time in your life No, I've never been there = at no time or 'That's the best meal I've ever eaten.' means the same as 'I've never eaten a better meal (in my whole life).

Thank you (;