Have a look at the cables and connectors, make sure they are fitting in correctly. Make a note of which connection points they are in on the TV, then select the appropriate input using the remote control - for example, the Wii may be connected via a SCART connector (it's quite big) and be listed by the TV as AV1, or something like that. The DVD may also be via a SCART or may be via an HDMI connector (it's about an inch wide).
We are a no TV household (although now we watch everything via the iplayer, it doesn't mean much!) - but last year, bought a physical TV set and Wii for our 2 DD for Christmas. We recently realised we could use this TV for watching DVDs (yes, I know - not very bright ... ) - but when we plugged in the specially bought DVD player which worked fine, the Wii seems to have stopped working, saying it doesn't recognise channels or something.
Is there a tech wizard out there who could very kindly give me some advice on whether I have missed something, or need a gizmo or gadget, or similar? Off to buy some bread now so I am not sitting here expecting instant wisdom to appear, but I would be very grateful for suggestions.