Can't open Music folder

Added some more files onto my Clip from my computer but now I cannot open “Music”, “Settings” although I can open the radio…

Take off the ones you just added and if that fixes the problem, you’re going to have to figure out which file is causing trouble. 

It seems like there may be a firmware issue. I suggest that you download the latest firmware, and manually install it on the player. Sometimes the copy of the firmware in the player becomes corrupted. Reinstalling the firmware is the way to fix corrupted firmware in the player.