Unable to listen to local files on Iphone

[familiedejeu]

Hi,

I downloaded all my local files from my computer to my Iphone and there is a green arrow next to them. But since I've changed the location in which the local files are stored on my pc, all the local files on my phone still have a green arrow but the titel is darkened and I can't play them. If I tap it, nothing happens, except a notification that pops up saying "Song can't be downloaded. You can synchronize downloaded songs from your computer" (something like that). And it then gives me the steps on how to synchronize the songs even though the green arrow suggests I've already downloaded them. Please help me!

Thank you!