240 volt reduced to 120

I have what I think is a bad light switch in my kids room. There are multiple outlets connected in here (3 of them are light switches for sure). My wife went to turn on our bathroom light when she heard what turned out to be electricl static and the lights would not come on. I checked the switch and it looks OK in the bathroom. I then checked the bedroom switch in my kids room and I could hear the same static when I reappplied the power to the breaker. This tells me this switch is more than likely the culprit. There are a total of 3 romex 3 wire cables leading into this box. I think one os for this switch in the kids room and the other 2 most likely lead to the bathroom switch and the other one to another light switch in a smaller bedrrom. I want to know what type of switch I should buy to replace this with and how to wire it up. The existing switch has 3 bars on top and 3 bars on the bottom that the wiring snaps into right now (original switch). the top 3 bars have 2 romex wires (for a total of 6 wires snapped into it and the bottom has the remaining wire. Balck to the left, copper in the middle, and white to the right terminals. I am sorry if I haven't given enought info. please let me know if there is anything else anyone needs to assist me in this matter. I know I should rewire the entire place but I am currently unemplaoyed which makes this not an option at this time. Thank you.

I replaced a sump pump that has a piggyback mercury switch on it. I wired the float switch off of the incoming black wire but the pump had three wires, brown, blue and yellow/green. I am pretty sure that the yellow/green was the ground but I dont know which one is supposed to be hot, the brown or blue. Or does it matter in this installation. This is only a 110 circit and I want to be sure that I wont' damage the pump by having it wired backwards. So as it is I have hot black to the switch to the blue wire and the green/yellow to the bare ground and the white neutral on the brown. Sound kosher? Also this pump is at the base of a ramp for a parking garage. Should the circut breaker have a GFCI at the panel?