iCloud backs up all device data, including audio files, to restore any lost files if they have been deleted. That means, if MP3s or songs were stored on the device during the last backup, an iCloud restore restores the files with no difficulty. Restoring from backups, though, replaces existing data with information from a backup, so it is recommended to always make and store backups of existing data first. For some, this may be a benefit. iCloud backups are mainly handy when used with an iPhone, which typically auto-syncs frequently. Keep automatic backups on to ensure audio is always stored. Read more: https://notchox.com/resources/how-to-recover-deleted-mp3/