A song that has always helped me immeasurably with loss, as it is specifically a song about coping with loss, is Machines by the Scottish band Biffy Clyro. In particular, this reminder that no matter how bad you feel, you can emerge from it as strong as before:

I’ve started falling apart, I’m not savouring life
I’ve forgotten how good it could be to feel alive
Take the pieces and build them skyward