Never

Never = (1) at no time in the past or future; not ever: ‘I’ve never met his wife.’ ‘I shall never forget this day’ (2) not at all; certainly not; not in any circumstances: ‘Never in my whole life have I been so offended!’ ‘I will never shop at that store again.’

Ever = at any time: ‘Have you ever met his wife?’

Ever is often used after a superlative: ‘His wife is the kindest person I’ve ever met.’

Never or not usually go immediately in front of a to infinitive: ‘He’s promised never to do it again.’

Do is used with never for emphasis: ‘You never did tell me why you decided to leave your last job.’

After nobody/nothing/rarely and other words with a negative meaning, use ever (NOT never): ‘After she won the national championship, nothing was ever the same again.’

Nevertheless = unlike but, nevertheless is an adverb (NOT a conjuction): ‘The survey was conducted on a very small scale. Nevertheless, the information gathered is likely to prove very useful.’ ‘As you may have heard, the existing workforce is soon to be reduced by 40 percent. The management is nevertheless committed to maintain the present level of production.’