Hi I have tried to install debian kali linux and my windows 8.1 together I was at the installing part when I lost electricity and my pc turned off when I turned on my computer a black page with a flashing - came and I couldn't boot my windows I really need my computer right now , any help pls ?
Looks like you damaged the windwos bootmanager when you was installing Kali linux. This answer should help you!– Stackcraft_noobJan 1, 2016 at 14:27
If you still have a copy of Win 8.1, go ahead and format your HDD (put it in another PC, and format it by using Disk Maganement). If not, go ahead and put your HDD in another PC and track the partition on which Kali should have installed and remove this and resize your Win 8.1 partition (also using Disk Management)
You replaced the windows boot manager when you installed Linux. It's a pretty common occurrence if you don't remove all of your storage devices before installation. I always pull my Windows drives before I install any of the distros that are Debian based. For whatever reason when it finds the first MBR it can see, it just erases it and installs Grub and an MBR on that drive.
I did this one time and unplugged my Mint HDD. It took me FOREVER to figure it out. Good luck with fixing your stuff.