What part of my manual would need repaired if my shifter does nothing?

Hello, When you say that a manual transmission is slipping, that immediately tells me the issue is likely the clutch. The shhifter will feel like nothing in all gears because there is no pressure applied to the transmission input shaft. The engine is basically spinning freely when the clutch is burned out. Remove the clutch inspe tion cover, I bet there's a ton of powder and debris from the clutch in there. 18 years isn't bad for any clutch!