Questions

1."I didnt do anything " This is standard English.

, " I didnt do nothing ",  This is black English or spoken by the uneducated.

and " I did nothing " ?  This is also standard English.  
Do these 3 sentences have the same meaning ? Yes, the mean the same.

2. What's the difference between " switch " and "change"?

"Switch" implies deceit, negativity or ulterior motive involved in some situations.  "He switched sides after hearing the scandal." Using "change" is neutral.  In some cases, they are not interchangeable. E.g., "He was switched at birth".

3.Can you give an example for the words " whom " and " who "?

"Who did you to?", "To whom did you speak to?"

http://www.grammar-monster.com/lessons/who_whom.htm

http://www.elearnenglishlanguage.com/blog/english-mistakes/who-vs-whom/

http://www.englishpage.com/minitutorials/who_whom.html

http://www.quickanddirtytips.com/education/grammar/who-versus-whom

questions

1."I didnt do anything " , " I didnt do nothing ", and " I did nothing " ?
Do these 3 sentences have the same meaning ?

2. What's the difference between " switch " and "change"?

3.Can you give an example for the words " whom " and " who "?

1.  "I didn't do anything" is grammatically corret.  You can't say "I didn't do nothing" because then you would have a double negative.  "I did nothing" is grammatically correct, but I don't think a lot of people would say it.  They do have the same meaning, though.

2.  Switch can mean that there are two things you want to change with each other.  For example, "I want to switch my dessert with yours."  That means that I'm changing my dessert with another person's.  However, you can also say "I want to switch partners."  If that's what you're saying, then it means the same thing as change.

3.  Whom is a preposition word.  Think of it as, "to whom, for whom."

Who is at the door?

I wonder who is at the door.

To whom are you giving the present?

However, people don't usually say "to whom."  In spoken and written English, it's much more common to say, "Who are you giving the present to?"