The device has either stopped responding or has been disconnected. Samsung S6, how can I fix this?

[AC Question]

The device has either stopped responding or has been disconnected." samsung s6

please can you tell me how i can fix this.....need to put 10 cds as mp3s on my phone and it refuses!!!! has moved loads of other stuff and still is. just rejects a couple and still does even though they are in windows media ...have tried this with windows 8 and 10
thanks