How many grammatical cases(noun declension) exists in Hungarian language?

Question

For ex, nominative, accusative, dative, genitive, instrumental...

Answer 1

There is a terminology problem with Western approaches to Hungarian grammar. There are actually only three cases in Hungarian--nominative, accusative, and possessive. All the other things which some old-fashioned grammarians call "cases" are not cases at all but suffixed postpositions. For example, let's look at the noun kutya 'dog'. The nominative is kutya, the accusative is kutyát, and the first person singular possessive is kutyám. These are the three cases.

There are quite a few suffixed postpositions. For example, kutyában 'in the dog', kutyából 'out of the dog', kutyába 'into the dog', kutyán 'on the dog', kutyára 'onto the dog', kutyáról 'off of the dog', kutyának 'to the dog', kutyánál 'at the dog', kutyához 'toward the dog', kutyától 'away from the dog', etc. These are the things that old-fashioned grammars called "cases".

Answer 2

According to the purists, none. There are words that can be squeezed into the usual categories (like the ones you list), but that's not really how Hungarian grammar works.