Local files greyed out and some not appearing

[Megarboh]

Plan

Free

Country

Hong Kong

Device

PC

Operating System

Windows 7

My Question or Issue

The story begins when I downloaded some new songs and added to my local file, but Spotify isn't showing those newly added songs.
And so I followed this "solution"
https://community.spotify.com/t5/Desktop-Windows/Not-all-local-files-showing-up-not-finding-albums-m...
And my new songs still aren't showing up. The songs' format is .mp3, allowed by Spotify, so it ain't the files' format problem. If I open them directly from the file and not from Spotify, I can listen to them perfectly fine, so the files ain't corrupted or anything.

So then I decided to use the "turn it off and on again" trick by cutting (ctrl + x) all my song in my local file, then pasting them back into the local file again. And somehow now not only my new songs are still not showing up, some my other old songs that used to be fine are now greyed out and I can't listen to them on Spotify anymore.

I then tried to designate Spotify to another local file by creating a new file and designate that new file as the new local file instead and paste all my songs to there including the new ones. My new songs are still not showing up, and some of the old songs that used to be greyed out aren't anymore, BUT some of my other old songs that weren't greyed out the last time are now greyed out.

I repeated the process above again, and this time the SAME THINg happened. Some of the greyed out songs are available again, but some other old songs that weren't greyed out the last two times are greyed out now. AND my new songs are still not showing up.