VirtualBox shows only 32 bit guest versions ― and how I fixed it

I recently purchased Lenovo Yoga 500 with 64-bit Windows 10. I installed Oracle VirtualBox on it but was surprised to find that I could only install 32-bit versions of OS on it. I found this article which suggested toggling Intel (R) Virtualization Technology and Intel (R) VT-d Feature settings in BIOS. But in my laptop I couldn't find this setting. Rather you will find a setting under Configuration tab called Intel Virtual Technology and enable it.

Reboot your system and now try to install OS in VirtualBox and it should now show both 32-bit and 64-bit versions of OS.