How to get rid of vbox error?

hey guys i am using VirtualBox
Version 6.1.12 r139181 (Qt5.6.2)

now my problem is every time i open a OS (be it kali,windows,tails,ubuntu)
it shows this error previously it was working fine
i had searched everywhere bt could not find solution for this hyper v is also disabled

Failed to open a session for the virtual machine Kali-Linux-2020.3-vbox-amd64 .


VT-x is not available (VERR_VMX_NO_VMX).

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


I would recommend you to use VMware.