Some of my contact lists disappeared the other day. I am using Skype 4.3 on Ubuntu 14.04. I am trying to move most of my communication to Slack, but some client

Some of my contact lists disappeared the other day. I am using Skype 4.3 on Ubuntu 14.04. I am trying to move most of my communication to Slack, but some clients and friends are still on Skype which makes this a pain for me.