ah ok, this sounds like it could be an issue with the ignition switch, which unfortunately isn't easy to swap on the later models because of the spline adaptor! The screw can just about be removed with a bent watchmaker screwdriver, so its doable but a bit fiddly.
I have found removing the entire column from the car makes this job easier:
1. remove lower ign cowl trim
2. disconnect all plugs to stalk & ign switch
3. undo and remove bolt joining steering rack UJ to bottom of column
4. pull wheel and it should come out with column still attached
Take care if it has an airbag, if so I'd disconnect the battery for 30seconds then remove airbag from wheel before you do anythign else. Its probably held to wheel with 2 allen bolts round the back, but not 100% sure on a Passat.
A quick n easy test to check if its the ign switch or not, buy a replacement and disconnect the ign switch plug from your car, plug into new switch. turn switch with screwdriver, if car starts its the switch, if not its something else!