I have a toyota camry 2000 and since I bought it the only horn that would work was the high tone one. All of the sudden none of them are working now. I realized that a relay on the fuse box that is under the hood on the left side clicks every time a press the horn pad. I need to check is the horns are blown at all and if the horn fuse is gone as well. How can I test the horns and where's the horn fuse box in the car?

The click you here is the horn relay, You need to find the horns and check for power at the wire connectors. But you probably have a bad low and now a bad high not horn. since the relay clicks your fuse is good so that eliminates the fuse.

Test the wires that go to it. Or replace them with another fuse or relay on the car.

If every time you press the horn pad,you
hear a relay click,
wouldn't it make sense, that the fuse is
good,the horn button works and the relay clicks.

Your not thinking

No the relays contacts maybe arced
The horns most likely are bad

Two things you can work on