Why isn't there a single band that makes songs like Nirvana used to?

A single band that would sound exactly like Nirvana would qualify themselves as wanna bes. I miss Nirvana too, but the Grunge era has run its course. I still think though, that the 90s has produced a lot of great rock. Now that's a sound I miss :( Thankfully, there are bands right now that maintain a certain raw sound. You might want to check out bands like Mute Math, Audioslave and Black Rebel Motorcycle Club. Audioslave still sounds like they came from the 90s and they're still kinda current. Black Rebel Motorcycle Club has been around for some years but I only heard of them a few weeks ago. They have a 90's rock feel to them but are also heavily influenced from rock bands from the 60s and 70s. Mute Math is not exactly new either. They're influenced by the 90s grunge sound but kinda better.

Nirvana is an American rock band.Although not my favorite, but I still really like.Which is your favorite Nirvana song?

There are in fact bands that are influenced by their music but developed and incorporated some of their own style with it such as Silverchair. I think that in that business, being unique is the key to stardom. They may either be great at a certain genre or just start their own genre. Kurt Cobain is said to have started the grunge era where in fact some bands have already played such music before but not as much as Nirvana did, and Kurt had made it to a level where his music became a new genre at the time.

It's just because of the geniality of Kurt. There will never be someone that can get close to the person he was. May he rest in peace...

Puddle of Mudd... Have ALLOT of Nirvana influence as well as Seether. No one really wants to sound like another band however., I have played music for 20 years and everyone says "You sound like KURT" not so much nirvana. Its the three verse chorus verse structure I believe. Never the less, I think it is good no one EXACTLY like them but their influence can be heard in many bands.