The car is a 1990 Chevrolet LTZ with power windows which are operated from a cluster of four switches ( one for each window) located on the inside panel of the driver's door. Three windows open and close perfectly. The left front window will not open. I DO NOT believe the problem is with the raising/lowering mechanism inside the door. My guess it that the problem is more electrical in nature. There may be a loose connection, or maybe the switch is worn out.

If the switch is worn out, will I be able to replace just the one switch for that window, or will I have to replace all four switches in the cluster?

Does anyone have any ideas or suggestions for repairing this situation?

Thank you

its probably a loose connection so you can remove the Assembly and try and get the connection tight again or you can buy a new switch or it could be that it needs to be cleaned in witch case you can buy some spay from a radio shack or electronics store and spay the switch until its clean. brake clean is good too its the stuff you clean your brake parts with to remove any grease. wear a mask and gloves. some times you can open up those pins that slide into the switch with a pointy thing(ice pick ) be careful
(a bottle of rubbing alcohol works too just use a old tooth brush)