How to transfer music?

Hello All,
Got a Blackberry z10 (Blackberry 10 Software release 10.3.2.2474, Operating system version 10.3.2.2639) with a sanDisk ultra 128GB microsd xc card. I have been trying for the last few months to tranfer 6,000 songs from my windows 7 laptop to the SD card. Have tried using Blackberry link software with the itunes as my music lister does not work, tried Blackberry blend, just using the windows explorer and even with the card card set as a mass storage device but most songs won't play. Get either media file (MP3) not supported or unable to play file. I am starting to wonder if I am doing anything wrong. I download Blackberry media sync (programme did not recognise my phone) also Blackberry desktop manager which also did not recognise my phone. Is there another way to transfer music to the sd card or a good media tranfser programme (freeware) out there? Any advice or solutions welcome