virtualbox.org

I have VirtualBox 4.12 installed on Windows Server 2008 R2 Datacenter (AWS EC2 instance). I want to create a x64 machine but there isn’t any listed in the VirtualBox.
Can anyone please help.

Make sure that hardware virtualization is enables in the PCs bios and that Hyper-v is not enabled in the Windows host.

HyperV is enabled by default and I don't seem to be able to disable it.

You have to decide. Only one VT-x/AMD-v (hardware Virtualizer) can access VMX ROOT mode at a time. You can use VirtualBox to run 32-guests but if you want to run 64-bit guests you will need to either be able to disable Hyper-v or remove it.

Thanks.
Hyper-V Tools check-box is listed in the Windows Features but it isn't actually checked or selected. So what else could be the problem here?

See my first response "bios"

I doubt that the OP can do anything about either Hyper-V or the BIOS settings on an AWS EC2 instance. It is probably a vm itself.

Yes that's right. So I have a situation here
Can anyone help please

There is no way that you can run a 64-bit guest in an OS running in a virtual machine. VirtualBox requires hardware virtualization to run a 64-bit guest, and obviously a vm does not have it.