I have really done it now! Took down the ceiling fixture to paint ceiling, and I knew better, but did not make note of how it was wired. This fixture is controlled by 2 three way switches. The ceiling box has 3 wires in it, red, black, and white, plus bare copper ground. The fixture has of course, only a white and black. I replaced the fixture by attaching the black and the white to the black and white of the fixture, and it works with only 1 of the switches. I know the red must connect to something, but before I make sparks, I would like to be advised where it goes. To the Black of the fixture with the black already in the box? Sort of sounds correct, but not sure. Any help will be greatly appreciated.

If you have red, white and black in box, The black from the light hooks to the red OR the black(unless something else was undone).

Thanks Stratmando. I made a mistake in my original post. Right now I have the fixture connected white to white, and the black of the fixture to the red in the ceiling box and it only works from 1 switch. The ceiling light worked perfectly from both switches until I removed the fixture to paint the ceiling. I just checked the ceiling box and indeed there are only 3 wires in it; red, black, and white, plus a bare ground. All 3 have caps on them, which I did not remove or add, other than to remove the fixture. I wish I had made note of how it was before I messed with it! The fixture now works from only 1 of the 2 switches. I did not remove or modify either switch or how it is wired. Maybe I should change how I connect the fixture at the ceiling box, to be white to white, and black to black, not black fixture to red in the box? In as much as all 3 wires had caps on them, obviously one was not used. Thanks again.

If you have red, white and black in box, The black from the light hooks to the red OR the black(unless something else was undone).
Are you saying you tried hooking the black from the light to the red, and then the red, and both do the same, different?

Thanks Stratmondo for taking the time to respond. I just went back to the room, and checked the wiring of the fixture to the box in the ceiling one more time. I checked the marettes (caps) on the fixture connection to be sure they were tight. Checked the marette on the unused black wire in the box to make sure it was on tight. Turned the breaker back on, and lo and behold the light worked as it should, i.e. either switch will turn it on, and either switch will turn it off. It is connected with fixture white to white, and fixture black to red. The line black in the box has a marette on it and is not connected to anything.
I sincerely apologize for having wasted your valuable time on what has turned out to be a non issue. Frankly, I have never understood the magic of 3 way switches or wiring, and I felt that I was in way over my head. Again, thanks to you for your insight, patience and quality of response. My world is a better place because people like you take the time to share your knowledge and expertise. As we say here in Quebec, merci milles fois, in English, A thousand thank you's

Hey, No problem, glad to of helped.