Light never turns off

Just a hunch, but worth investigating.

I suspect you have this light fixture somehow linked into two circuits. That should never happen, but if it does, you can end up with a lot of strange things.

Find the Breakers

You need to figure out which breaker controls the switch and which breaker controls the light separate from the switch. Doing that may get a bit tricky, as I would not connect the switch back to the light again until this is straightened out.

I would get a non-contact tester and/or a multimeter to test the switch wires. You should see one of the wires hot (lit up with the non-contact tester) and 120V (assuming US for the moment) between the wires. When you turn off the relevant breaker you should no longer see a hot wire and the voltage between the wires will either be zero or some relatively low phantom voltage.

When you have the switch breaker off, does the light go out? If it does, then the next step is to check each other device (light, switch, receptacle, built-in appliance) on the same circuit (i.e., everything that goes off when you turn off that breaker), looking for loose wires, things wired incorrectly, etc.

If the light stays on when the switch breaker is off then you have to keep flipping breakers until you find the one that turns off the light. Then you know that you have a cross-connection between the two circuits which is NOT a good thing. That could take take several forms, and will likely require checking out the wiring on both circuits. But I would actually start in that case with the wires going into the problem light fixture. One possibility is that wires for the 2nd circuit pass through the ceiling junction box and that when the light fixture was replaced, the wires got messed up. But there are other possibilities as well.

In some places there are two switches to turn on and off lights check the switch you would use to turn off and on if there are two switches to turn on and off lights check the wires in the second switch there will be 4 wires if its connected by two switches there will be a black wire and either a blue or red wire then a ground you want to connect the blue the black group if it's red you connect the wire to a silver screw the black wire goes to gold then make sure the switch on the other one has a black and white wire connect them correctly if that doesn't work the light connected to the switch may need to be replaced which is still an easy fix all you have to do is take down the light make sure you turn off the breaker first when you are able to see the black and white wires if it's connected to two switches there will be two of each wire two blacks and two whites make sure they are tightly capped together then connect the wires back to the correct colored wires for the light that still doesn't do it remove the second switch and cap the wires go back to the first witch and make sure you can turn it off and on that is if there are two switches usually in this case there are two switches to do so in all the time that I've replaced outlets and switches for lights there have been two usually the fixes because one of the other ones are having a harder time corresponding with the others if that doesn't work I would suggest you call an electrician because there could be a problem with the wiring to and from the switch