Inversion 1:

After Negative or Limiting Adverbs

Inversion happens in English for emphasis, dramatic purpose or formality. This type of inversion uses negative and limiting adverbs these are a group of adverbs which limit the meaning of a verb or make it negative. Examples are:
never, hardly, no, rarely, seldom, little, barely, no sooner...than, in no way, under no circumstances, nowhere, not (+time), (only+ time). (This is not a complete list.)

To invert a sentence move the adverbial to the beginning of the sentence and invert the subject and auxiliary verb:

‘I had never met someone so interesting.’ becomes ‘Never had I met someone so interesting.’
'He **won't often go to work.' becomes 'Not often will he go to work'
'You **should not leave this room for any reason' becomes 'Under no circumstances should you leave this room.'
'She **hasn't seen him anywhere.' becomes 'Nowhere has she seen him'

**Notice that if the auxiliary verb is negative in the first sentence, it becomes affirmative in the inverted sentence and the 'not' moves to the front or "inside" the meaning of the adverb at the beginning of the new sentence.

In cases where the tense does not use an auxiliary verb in the affirmative, such as the present simple (do/does) or the past simple (did), one must be added.

Present Simple:
‘I rarely go outside.’ becomes ‘Rarely do I go outside.’
'They don't even know what to do' becomes 'Never do they know what to do.'
'She almost never loses' becomes 'Scarcely does she lose.'

Past Simple: (Notice how the verb changes from past tense to infinitive)
‘She seldom worked very hard.’ becomes ‘Seldom did she work very hard.’
'We never went to the shopping centre.' becomes 'At no time did we go to the shopping centre.'
'He didn't react at all.' becomes 'In no way did he react.'

Inversion 2:

Some negative or limiting adverbials require you to complete a whole adverbial clause before the inversion takes place.

‘I didn’t know what to do until I saw what had happened.’ becomes ‘Not until I saw what had happened did I know what to do.’

In this case, ‘Not until I saw what happened’ is the adverbial clause. The inversion takes place after this, in the main clause. This happens with 'Not +time' and 'Only + time'.

Not + until / before + clause with the inversion
Only + when / as / after / while / once + clause with the inversion

Other examples are:

'Only when they met again did he tell her'
'Not before he admitted the truth did they let him go'
'Not since Paris had they seen such a beautiful sunrise.'
'Only now could he see how wonderful a car it was.'

Inversion 3:

'Hardly' puts the inversion in the adverbial clause. It uses 'than' and 'when' to connect with the main clause.

‘Hardly had I got home than the dog started barking.’ (Apenas / poco después)
'Hardly had he got into the bath when the phone rang.’

Inversion 4:

Little did they know means they didn't know. The subject can be changed. Little can also be combined with nouns to show a lack of something, such as food or time.

‘Little did they know that he had stolen all of their money.’ (They didn't know he had stolen all of their money)
'Little did he know that they would never meet again.' (He didn't know that they would never meet again.)
'Little time did they have to explain.' (They didn't have time to explain)
'Little patience does she have on a good day!' (She doesn't have any patience on a good day!)

Here are some negative adverbs and adverb phrases that we often use with inversion:

Hardly puts the inversion in the adverbial clause. It uses 'than' and 'when' to connect with the main clause.

Hardly had I got into bed when the telephone rang.

Never

Never had she seen such a beautiful sight before.

Seldom

Seldom do we see such an amazing display of dance.

Rarely

Rarely will you hear such beautiful music.

Only then

Only then did I understand why the tragedy had happened.

Not only ... but

Not only does he love chocolate and sweets but he also smokes.

No sooner

No sooner had we arrived home than the police rang the doorbell.

Scarcely

Scarcely had I got off the bus when it crashed into the back of a car.

Only later

Only later did she really think about the situation.

Nowhere

Nowhere have I ever had such bad service.

Little

Little did he know!

Only in this way

Only in this way could John earn enough money to survive.

In no way

In no way do I agree with what you're saying.

On no account

On no account should you do anything without asking me first.

2: We can use inversion instead of 'if' in conditionals with 'had' 'were' and 'should'. This is quite formal:

Normal conditional: If I had been there, this problem wouldn't have happened.
Conditional with inversion: Had I been there, this problem wouldn't have happened.

Normal conditional: If we had arrived sooner, we could have prevented this tragedy!
Conditional with inversion: Had we arrived sooner, we could have prevented this tragedy!

3: We can use inversion if we put an adverbial expression of place at the beginning of the sentence. This is also quite formal or literary:

On the table was all the money we had lost. (Normal sentence: All the money we had lost was on the table.)
Round the corner came the knights. (Normal sentence: The knights came round the corner.)

4: We can use inversion after 'so + adjective...that':

So beautiful was the girl that nobody could talk about anything else. (Normal sentence: the girl was so beautiful that nobody could talk of anything else.)
So delicious was the food that we ate every last bite. (Normal sentence: the food was so delicious that we ate every last bite.)

Inversion 1: After Negative or Limiting Adverbs

Inversion 1: After Negative or Limiting Adverbs