Why does virtualbox only have 32-bit option, no 64-bit option on Windows 7?

Take a look: http://www.fixedbyvonnie.com/2014/11/virtualbox-showing-32-bit-guest-versions-64-bit-host-os/

If VirtualBox is only showing 32-bit versions in the Version list make sure:

• You have an x64 CPU installed. (Optimally, a 64-bit OS should also be installed to receive acceptable virtualization performance.)
• Hardware virtualization is enabled in the BIOS. (Your CPU must support it.)
  • For Intel x64: VT-x (Intel Virtualization Technology) and VT-d are both enabled
  • For AMD x64: AMD SVM (Secure Virtual Machine) is enabled
• Hyper-V (or any other form of bare-metal hypervisor) is not installed

If you want to emulate 64 bit apps on a 64 bit host, your cpu needs a feature for that. Which duDE says, is an intel-specific copy-paste. The same support exists on AMDs too, there its name is AMD-v - maybe he forgot to mention.

If your cpu doesn't have this support, it won't ever work. If it has, maybe you need to switch this on in your bios.

There are bad BIOSes which can't turn this feature on. Sometimes a BIOS upgrade can in this case help.

Had the same problem, only seeing 32-bit versions for the host OS's. Started working after updating asus p8z77-v pro bios to latest and enabling virtualization support. Before the bios update, virtubox showed only 32-bit OS's.