finding my missing music files

I tried to download all my music from MacBook to my iphone. I chose to have it be in the cloud (I think). After that my music was gone on my MacBook and most of the music on my iphone. I've been on with Support gone to Time Machine. Looked at the removeable hard drive and it seems to be scattered all around. Some are just not even showing up at all. These are files I've saved over decades downloaded to my computer and some I even downloaded from CDs. None of it it Apple music which was purchased. There seem to be hundreds of files empty or just missing. Any suggestions of how to herd these wandering cats and get them all back together in a happy home music file ?