HOW TO USE INDEFINITE PRONOUNS

Words like 'something', 'everywhere', 'anybody' and 'no-one' are indefinite pronouns. We use them for people, things and places.
People: somebody* / anybody* / nobody* / everybody*
Things: something / anything / nothing / everything
Places: somewhere / anywhere / nowhere / everywhere
*We can use anybody or anyone - the meaning is the same. It's also true for someone, no-one and everyone.
These are singular words, so we use a singular verb with them.

-Does anybody want cake?

-Everybody loves the new puppy.

However, we can use 'they / them / their'.

-Anybody who wants cake should pass their plate.

-Nobody brought their bag.

We can use these words on their own for a short answer.

A: What do you want to eat? B: Nothing!

We can use them at the beginning of a sentence as the subject or as the object of a sentence.

-Nothing was done.

-She did nothing.

Some- and any- We have already talked about how to use some and any. 
We use someone / somebody / something / somewhere in the same way as some and we use anyone / anybody / anything / anywhere in the same way as any. We use somebody / something / somewhere mainly in positive sentences.

-We can find somebody who can help.

-There's something in the bag.

-Let's go somewhere this weekend.

We use anybody / anything / anywhere in the same way, but for questions and negative sentences.

-I can't find anybody who can help.

-Is there anything in the bag?

-We didn't go anywhere this weekend.

We also use anybody / anything / anywhere with sentences that have a negative feeling.

-There is hardly anybody here.

-She ate hardly anything.

-We spent the weekend at home without going anywhere.

We can use somebody / something / somewhere in questions when they are offers or requests or when we think the answer is yes.

-Are you looking for something? (= I think you're looking for something.)

-Would you like something to eat?

We often use anybody / anything / anywhere after 'if'.

-If anybody would like a coffee, tell me now!

-If anything is wrong, you need to phone the reception.

-If there's anywhere that you don't want to go, please send me an email.

We also use anybody / anything / anywhere with the meaning 'it doesn't matter who / which / where'.

-Anybody can do this.

-I'd like to go anywhere! I just don't want to be here!

-She was so hungry that she ate anything.

No- Nobody = not anybody. Nothing = not anything. Nowhere = not anywhere.

-I don't know anyone who's coming = I know nobody who's coming.

-There isn't anything here = there's nothing here.

-She doesn't want to go anywhere = she wants to go nowhere.

Usually the sentence with 'no' is stronger and more emphatic.
We don't usually use a negative verb with nobody / nothing / nowhere. Sometimes you hear this but it's not standard English.

NOT: I don't know nobody.

Every- Everybody = all the people. Everything = all the things. Everywhere = all the places. These can be used in positive sentences, negative sentences and questions.

-I think that she has been everywhere in Europe.

-He doesn't know everything.

-Do you know everybody here?