Windows Media Player

Is it possible for Media player to get to full to hold more music?

I wouldn't think so. Apparently there is some kind of issue. Would you explain it in more detail?

when I try to download a song,it will not come into the media player unless I delete a song. Like there's no more room

Are you using a FAT32 hard drive? There's a limit of either 2 or 4 Gb (I can't remember for sure) on a Folder size. If you put the downloaded file into a separate folder from the music Library and drag and drop it into WMP, will it play.

I had to have it replaced, I don't know what it is,

Did you try the drag and drop?