How to transfer music files from computer to HTC One mobile phone
It's a pain in the neck that Google decided that SD cards (with FAT32 file system) were "prone to corrupted filesystems" and decided that we're best off with Microsoft's MTP (Media Transfer Protocol)...we're too dumb to manage our own files and folders.
I'd recommend getting Ghost Commander and the Ghost Commander SMB Plugin (for navigating to Samba [Windows] file shares)
Share the folder you want to copy music from from your Windows (or Linux box with Samba installed), and copy the music files to the Music folder on your device. It may be easier to copy an entire folder at once. You may have to type in a username and password if you decide to password-protect the share. (You can save the share as a Favorite in Ghost Commander to make things easier in the future.)
AirDroid is a nice alternative if you want to do the file management from your Windows machine.
Try AirDroid, SnapPea, or ,a href="https://www.pushbullet.com/">Pushbullet if you need to do files from time to time.
Depending on whether or not your computer has bluetooth and the right bluetooth services, you can pair your phone with your computer and use your phone to "share" your music to your computer.
Susendeep D suggestion is to be considered
you can try alternative like Airdroid
How to preview, import or export music? And how to set music as ringtone?
I second the HTC Sync Manager but you can also use other tools like
Windows Media Player
doubleTwist [if you are using iTunes]
You can use HTC Sync Manager to transfer all the music into your phone.
See the link below to know what it can do more -