Thanks. That worked. Now how do I get my music files? I have a new - empty - computer.
Unfortunately unless you've backed them up to something like an external USB hard drive, cloud file storage service, etc. then you can't. Maintaining the storage/backup of their media files is up to the user, and they need to know that MC doesn't backup their media files or anything like that. Users have to do that themselves using internal hard drives or external hard drives or cloud file storage services, etc.
If all your media files are lost and can't be recovered, you'd also have to start over. If you don't have a backup of your media files anywhere, then unfortunately you'd have to start over. And if that's the case either way, I'd
highly recommend storing them on a separate drive, like a external USB hard drive, even if it's a backup because losing all your media files isn't fun at all. Do not store your files on the same drive your OS is installed on - if the OS goes belly up and you have to reformat, you may not be able to recover your media files.