I have a Windows 10 Home machine (Lenovo Y520) with a Core i7-7700HQ processor. Windows 10 and the BIOS are up to date. So is Oracle Virtualbox.
Until recently it was running VMs just fine with Oracle Virtualbox (doing what I bought it to do). Then it stopped doing that. VirtualBox's New VM feature stopped offering me 64-bit VMs. The ones I already had in place stopped running.
I have tried the instructions in these answers:
Why does virtualbox only have 32-bit option, no 64-bit option on Windows 7?
VT-x is not available, but is enabled in BIOS
Specifically, I've tried upating the BIOS, reloading BIOS default settings, turning on Intel Virtualization in the BIOS, rebooting, powering off and back on again, etc etc ad nauseam. W10 Home doesn't have the Microsoft virtualization features that often interferes with VirtualBox, and I've made sure Windows Hypervisor Platform is shut off.
Still, no 64-bit vms. What next?