The top switch on my wall switch is no longer working. I replaced the switch but the same thing is happening. The lamp works on another switch so it isn't the lamp. Any ideas?

You say switch, but do you mean receptacle? Not sure what issue you are having and not sure with what device you have a problem. Can you be a bit more descriptive with the situation?

You mention that it works with another switch so we assume this is at least a 3 way switch. Did you replace the old switch with a 3 way, 3 screws on the sides and no ON?OFF marking?