I have downloaded music from my laptop to my Samsung, it appears in my files but not in Google play music when I choose to play it from the files, it says "error track cannot be played". Any ideas on how to fix this?
1. The "error" could be because the file extension on the phone doesn't match the type of file it is. In other words, if you rename an .ogg file to .mp3, because you don't have an ogg player, it's not an /mp3 file, so an app that plays mp3 files can't play it.
2. Music apps get their lists of files to play from Media Scan, which scans the phone when you start it and builds a database of media files (music, pictures, videos, etc.) It's faster for the music app to just ask for all the mp3 files, or all mp3 and wav files, than for each app to scan the whole phone. Downloading files doesn't trigger the media scan. Restart the phone.
IF you have an app that can play the types of files you downloaded, they'll show in that app. If not, you'll have to find an app that plays that type of file.