How can I download my offline local music from my phone

[FireTendencies]

So pretty much I had local music in my PC and I offline downloaded it in my phone in a playlist. Long story short I formatted my PC and lost all the local music and thought I lost it from Spotify since it disappeared from the desktop client (obviously) but I was surprised they are still on my phone. So how can I download them back ? I don't mind having to use only Spotify to listen them I just need to make sure I won't lose them.

[FireTendencies]

Phone is rooted btw.