It sounds like you've got the wrong input selected. You will have a button on your remote control which will allow you to select the aerial or one of the sockets used for \dvd players, satellite dishes etc; you have probably hit the button accidentally and your TV is looking for an external device. Either that or you're trying to watch from an external device which isn't powered on.
I think you have your TV set looking at the DVD input, since you can watch it via your DVD recorder. If you want to watch a programme via the aerial, you will have to use the button on the remote to change the input source to "aerial" (or whatever Toshiba call it).