Changing two switch to one switch
The switches were probably (almost certainly) wired like this:



This is the method to have two switches operate one light, common for stairs etc When either switch moves to the dotted position, then the light is on. If both switches are in the dotted position then the light is off as it is in the position shown.

What you need to do is to make a connection between two of the wires you capped off then the other switch will work fine. If you connect two and it still does not work then you have to use the third wire with one of the other two.

The original fault sounds like a broken switch anyway.

If you are not sure then it will be an easy job for an electrician either new switch or connect the wires...