Can't run 64 bit Linux on Windows10 64bit

I am trying to run Virtual Disk Image, which is 31Gb, on my Windows through virtual box, but my virtual box not showing 64bit, only 32bit. But in order to run the OS, I need Linux 64bit. I googled it and tried to enable the Vt-x on my BIOS, but still didn't help. What are the other possible ways for this kind of issue?
Here is the error code and message

VT-x is not available (VERR_VMX_NO_VMX).


Result Code: 
E_FAIL (0x80004005)
Component: 
ConsoleWrap
Interface: 
IConsole {872da645-4a9b-1727-bee2-5585105b9eed}