Something, anything, everything, nothing etc.

    Don't tell anyone. 

Someone, somebody, something, anyone, anybody, anything, everyone, everybody, everything, no one, nobody, nothing are pronouns.

Somewhere, anywhere, everywhere and nowhere are adverbs.

There are lots of possibilities. Here are some examples:

We can use anyone etc. after 'if' or the idea of 'if':

If anyone needs help, please ask.

Anything you can do to help will be useful. [if you can do anything]

We use the 3^rd person singular verb with all these pronouns. For example:

Someone is going to call me back.

Is anything wrong?

Everything looks great.

No one wants to go to the meeting.

The pronouns can be used as subjects or objects:

Anyone can come to the seminar.     I didn't see anyone I know at the seminar.

Note that:

1.    Someone = somebody

       anyone = anybody

       everyone  = everybody

       no one  = nobody

       There is no difference in meaning. They all refer to people and we can use 'one' or 'body'.

2.    No one is sometimes written as 'no-one'.

3.    Something, anything, everything and nothing refer to things.

4.    Somewhere, anywhere, everywhere and nowhere refer to places. 

5.     No one and nobody = 'not anyone' and 'not anybody'.

        Nothing = 'not anything'.

       'Not everyone' is not the same as 'not anyone'. For example:

I went to the seminar but I didn't speak to everyone. [I spoke to some people but not all.]

I went to the seminar but I didn't speak to anyone. [I spoke to no one.]

You can ask anyone in this team for help - they're all experts. [it doesn't matter who.]

Can you get me a cold drink from the canteen? Anything will do. [it doesn't matter what.]

I don't mind where we go tonight. Anywhere will be better than staying at home. [it doesn't matter where.]  

We only use everyone to talk about people and 'every one' to talk about people or things. 'Every one' is different because there is more emphasis on each or every individual person or thing in a group, whereas everyone is more general and refers to a group.  

Everyone who organised the conference did a great job. [the group]

 We need to thank every one of them. [each individual]

I made hundreds of sandwiches but the delegates managed to eat every one.

.

These have the same meaning but 'not' + anyone, anybody, anything and anywhere are more commonly used. No one, nobody, nothing and nowhere are considered more emphatic:

Although the pronouns take singular verbs, we sometimes use 'they', 'them', 'their' and 'theirs' rather than 'he', 'she', 'him', 'her', 'his', and 'hers' with those relating to people. For example:

Someone gave me their ticket so I can go to the concert.

If anyone understands this, can they explain it to me, please?

Everyone needs to understand their responsibilities.

No one has finished writing theirs yet.

We often do this when we don't want to specify a gender. It is much better than using 'he or she' or 's/he', for example.

'Not anyone' etc. isn't usually used at the beginning of a sentence or clause:

Not anyone has to work at weekends.

Not anything was provided. 

We looked for a hotel but not anywhere in the city was suitable.  

Instead, we use no one or nothing or nowhere:

No one has to work at weekends.

Nothing was provided.

We looked for a hotel but nowhere in the city was suitable.

However, we can use 'not everyone'.

Not everyone is happy about the new rules.

I tried to explain that not everything about this job is easy.

The pronouns beginning with 'any' can be used in affirmative sentences which include a word with a negative or restrictive meaning:

We rarely invite anyone here in the winter - the roads are too dangerous.

It's unlikely that we'll receive anything before the end of the week.

We failed to find anywhere that was suitable for the conference.

We also use it in clauses beginning with 'before': 

Let's deal with it now before anyone complains.

Before buying anything for the new office, we should decide exactly what we need.

We do not usually use someone etc. in negative sentences:

I don't know someone there.   

I don't know anyone there.        I know no one there.            

However, it is possible if, for example, the person is unknown or we avoid naming the person or we are being ironic:

     Someone didn't remember to lock the door last night.

Or with 'something':     Something isn't right here.    I didn't do something wrong.

We use intensifiers to give extra information. Here are some examples:

   We talked to someone who gave us some good advice. 

   "Do we have everything we need?"   "I think so. Nothing seems to be missing."

    If anyone has any good ideas, this would be a good time to tell me. 

  I prepared all the food myself, without anyone to help.

   Have you seen my keys? I can't find them anywhere.

   Not everybody takes a suitcase - some people just have hand luggage. 

    There's absolutely nowhere I'd rather be right now!