Vickiemotox - welcome to the forum.
Have you tried a soft reboot of the youview box .
Press the Standby button on the Youview box for 8 seconds or more and the box will reboot.
Do the channels reappear after that reboot ?
What Tv package (Essential , Entertainment etc) do you have and what other channels are you missing ?
When you say missing do you mean they don't appear in the TV guide (EPG) or that they don't play.
