If you use an antivirus (something like Avast), it might of bugged out when trying to update the launcher/replacing files. I've had that happen a couple times. Fixed it by having my girlfriend send me her updated/patched boot folder and replaced the entire boot folder in the install folder. It would then run the client update properly. If you have someone that can zip the updated boot folder up and send it to you try that if you haven't.

Reinstalling probably works too as a last resort.