For help with your TalkTalk TV box, channels and apps.
Monday
Help
Monday
if you have the TV Hub or 4k box this is known to happen.
The reason is not clear, but it is suspected its due to a low signal on C5 which somehow triggers the app to disappear.
Try turning off the box for around 30 minutes, or maybe overnight from the mains and see if it reappears.
If not then you will need to do a factory reset, which will mean you will also have to sign into your apps again.
How to reset your box can be found here
Monday
A bit more information would help us to help you. On what device?