Welcome to the Community Forum. Sorry to hear that your IPTV app isn't working. If other apps are working fine, then this indicates a problem directly with the app, which we don't support, but perhaps someone from the Community can offer some advice.
Have you tried looking online for troubleshooting tips with IPTV?
We can suggest uninstalling and reinstalling the app, but again, if you have saved content, it may be lost.
Please let us know how you get on with this.
Virgin Media Forum Team
Need help changing SIM card? Find out more about activating your 4G ready SIM. 4G SIM Swap Help