In my case I always like listening to “A whiter shade of pale”, it always works.
“You Are The Blood”, the Castanets. Maybe it’s the game I first was exposed to it from, but it just sounds like… “It’s all over. Let your muscles go slack, let your trigger finger untense.” It sounds like what I imagine the peace of death to feel like.
Fade to black, Metallica usually.
Usually the entire soundtrack of the Ori series: Ori and the Blind Forest & Ori and the Will of the Wisps. In particular, my favorites to calm down is “Separated by the Storm” and “Ori, Embracing the Light”
Oh Wonder’s self titled Album. The first one is pretty relaxing.
Anything by The Midnight or by Gunship
This might sound childish, but there’s an old EP of lullabies that my parents used to play and sing for me long ago. Decades later, I got a copy to play and sing for my own son.
It’s called Golden Slumbers: Lullabies From Near and Far (1956). It’s not available digitally and was never released on CD, so I ripped the EP and posted it to YouTube at the link above. It’s really relaxing.
Necromancing Dancing by bear ghost can lift my mood regardless of why I’m upset. but it usually 'Depends on what I’m upset about. I try to find a song that is about the issue I’m experiencing. It helps me better articulate why I am upset I guess.
A Warm Place by Nine Inch Nails
Don’t Stop Me Now by Queen. No matter how bad I feel, it always makes me feel better, and it’s lively enough that it inspires me to channel that energy into somehing more productive than just venting.
Dizzy Wright - Killem Wit Kindness
This song always helps me realize how being upset is really nothing more than a barrier to clear thought and working past differences. Great jam to boot too!
Whiter shade of pale is beautiful
This is definitely too extreme for most people but I like “Bring Me The Head of The King” by Man Must Die
It’s angry enough for angry me to be okay listening to it but within a minute or so I’m in a better mood because I just like the band.