Use of Much, many and a lot.

"Much", "many", and "a lot of" indicate a large quantity of something, for example "I have a lot of friends " means I have a large quantity of friends.

Much, many, and a lot are quantifiers.

Study the examples below:

How much money have you got?	I haven't got much money.
	I have got a lot.
	I have got a lot of money.
How many students are in the classroom?	There aren't many.
	There are a lot.
	There are a lot of/lots of students.

In the interrogative forms we use:

• much with uncountable nouns. (money, bread, water...)
  Example:
  How much money/bread/water...is there?
• many with countable nouns. (students, desks, windows...)
  Example:
  How many students/teachers/desks... are there?

In the negative forms we use:

• much with uncountable nouns. (money, bread, water...)
  Example:
  I haven't got much money/bread/water...
• many with countable nouns. (students, desks, windows...)
  Example:
  There aren't many students/teachers/desks...

In the affirmative forms:

In spoken English and informal writing we tend to use:

·         a lot, a lot of, lots of with countable and uncountable nouns.
Example:
"How many students are there in the classroom?"
"There are a lot."
"How many students are there in the classroom?"
"There are a lot of / lots of students"..

In formal written English:

·         It is also possible (and preferable) to use many and much rather than a lot of, lots of and a lot in formal written English.
Example:
There are many students.
Much time was spent on studying.

So if you're speaking or writing to friends (informal), use a lot, a lot of, lots of. But if you want to be more formal, perhaps it is preferable to use much and many.

Remember:

In affirmative sentences with so, as or too, we also use much / many.

Examples:
"Carla has so many friends."
"She has as many friends as Sue."
"Kevin has too much money."

Summary:

Interrogative	Negative	Affirmative
How many books are there?	There aren't many.	There are a lot.
		There are a lot of books.
		There are lots of books.
		There are many books (formal)
How much money have you got?	I haven't got much.	I've got a lot.
		I've got a lot of money.
		I've got lots of money.
		I have got much money (formal)