While I can’t think of an album that reminds me of the world before 9/11, I can definitely think of an album that reminds me of the date. Slayer’s God Hates Us All released on September 11, 2001after being delayed due to mixing issues, resulting in the coincidence. They even make a couple references ot terrorism.

I was a teen at the time and while a lot of this is personal taste, I think Offpsring’s Americana just really nailed it for me. The whole album, but the titular track in particular, https://www.youtube.com/watch?v=GtzKW_ONjJ0

9/11 wasn’t a surprise in a lot of ways, we really felt it coming. Afterwards, in the early 00’s that followed, I remember less of the alt and punk rock and a lot more of the cleanly produced emo pop punk taking over. Stuff like Alkaline Trio (From Here to Infirmary), The Ataris (So Long Astoria), Something Corporate (Leaving Through the Window), and Saves the Day (In Reverie). Appealing to angsty teens has always been like shooting fish in a barrel (see Sonic Youth or Nirvana) but in retrospect, it’s hard not to see that widespread, mainstream appeal of emo as a reaction to something.

EDIT: The Kids Aren’t Alright

As an aside The Coup had this artwork for a mid-September 2001 slated release. They pushed the date back and changed the cover.

I was already in my 30s when 9/11 happened, and I can’t say I noticed any change in music attributable to it.

I was 10 when 9-11 happened so not much, but Mark Knopfler’s Sailing to Philadelphia always takes me back, released in 2000 and I remember being in the car with my dad listening to it