The issue is fixed, I had forgotten to change boot mode and boot priority in BIOS to UEFI and UEFI First, and also 'Optimize for' from 'other OS' to 'Win8 64bit'
First of all, sorry if this question has already been answered. There are so many questions of this topic, and I can't read answers of all of them, read some of them but they weren't helpful.
So I installed Ubuntu on my Lenovo laptop alongside Windows 8.1 UEFI (dual boot) and now I cannot boot to Windows 8.1. 🙁 When I restart, GRUB boot manager asks me the OS to boot from. When I select Ubuntu it just loads fine but when I select Windows 8.1 I get the following error:
windows failed to start. a recent hardware or software change might be the cause. to fix the problem: 1. insert your installation disc and restart your computer. 2. choose your language settings. 3. click repair your computer. File: \Boot\BCD Status: 0xc00000e Info: The boot configuration data for your PC is missing or contains errors.
I don't have any installation disc can I fix this by booting to Ubuntu? One of my friend suggested to do:
sudo apt-get install syslinux sudo dd if=/usr/lib/syslinux/mbr.bin of=/dev/sda
But I'm afraid to execute those commands as I don't know what they will do. Any advises?