I have install Windows 8.1 and Ubuntu 14.04 on my PC. But when I am turning on my computer, ubuntu boots automatically and i can not boot windows.
What can I do about it?
Press and hold shift as you see the BIOS screen until you get a list of bootable Operating Systems. If Windows isn't there, you have probably accidentally removed it...
try running osprober
see if it detects your windows.
Also while installing did go into your bios and disabled fast boot
or secure boot
.
Might be a UEFI issue.
sudo fdisk -l
and edit your question with the results.