My 25''zenith color TV has white lines running vertical to horizontal on screen and the picture is really blurry. Impossible to watch. Help please.

White, vertical lines. I'm not sure what "vertical to horizontal" means (diagonal?). Blurry. Sounds bad.

While I don't like saying this, (and it probably could be repaired, but it will probably cost more than the TV is worth), "TV is toast".

Could also be a bad antenna connection, giving a very weak (analogue) signal.

Is the problem equally bad on all channels, or are some worse than others (the latter would suggest a signal strength problem)?

Try wriggling the antenna connectors at the set and at the wall. If you have a spare indoor antenna, try plugging that into the set in place of the outdoor one, to see if it's any better (just as a temporary test - the problem could be up at the roof end of your antenna system - this will save you going up on the roof to check).

Daniel