My dualboot laptop wont start windows 8

Hello,

Hello, my laptop had windows and linux at the same time, before but today, windos tried to update and it failed but it gave a blue screen of ''failed to update, uninstalling updates, dont turn off your laptop'', its been doing this for over 5 hours now, i have checked to see if ubuntu works and its ok. what is the problem with window 8.1- remember i have been using a dual boot for over 6months, until todat?