A computer screen should never be sprayed or wiped with Windex. Ammonia and alcohol-based cleaners can damage an LCD screen. Water and a cloth are typically effective enough to clean a computer screen.
Clean a computer screen with a clean, soft cloth or paper towel dampened with water. Use a gentle, circular motion to wipe the monitor. If the screen is heavily soiled, a solution of 1-part distilled water and 1-part white vinegar can be applied to a cloth and wiped onto a computer screen. Unplug the computer or turn off the monitor before cleaning it to avoid shock or electrical damage, and air-dry or wipe the screen with a soft, dry cloth before turning on the monitor.