I'm getting a white screen when I log in to my WHM sonic cpanel
This is a known issue by the developpers at WHM Sonic when your account has exceeded the quota
You will need to erase some of your files (mp3s) and get back within your allowed quota
This can be down with a ftp client using your account info
Using your account login info , You can use a popular ftp client like Coreftp
http://coreftp.com