Hi She4 👋 welcome to the community! Thank you for posting.
Sorry to hear you are having some difficulties with your landline following a landline switchover.
You should have received an adapter in the post ahead of the switch that you use to connect the landline handset to the hub. You can see more information about this here (including pictures of the adapter!) 👉 Switchover_Migration_Leaflet.pdf (virginmedia.com).
Please let us know if you have not received an adapter and we will send you a PM to confirm a few account details and get one sent out to you ASAP!
All the best 🌞
Molly