you are right
it will be NH4NO2 but small amounts of NO and HNO3 are also produced in this reaction.
I wanted to know which reagent might be used and equation of the reaction that will take place on using that reagent
Just gently warm the above mentioned compound, as it is not an innocent compound. In fact, it is an explosive material.
Heating it gently will yield N2 and water. If NO is formed (I don't know how), you can pass this gas first through a supply of oxygen. Oxygen will convert NO to NO2. Now pass this mixture through water. NO2 is soluble in water, yielding Nitrous and Nitric acid.
Nitric acid formed in the reaction will just stay in the solution, no need to worry except when handling the solution. You got yourself a good yield of Dinitrogen.
In my opinion, if you want high lab yield of Dinitrogen gas, you should heat alkali metal azides.