Black Screen with cursor blinking when started Ubuntu on VirtualBox

Ubuntu on my Virtual Machine was running fine when I restarted then suddenly it starts showing a black screen. I googled and tried multiple solutions like:

  1. by disabling the “Enable 3D acceleration” on virtualBox settings
  2. Enabling the “Intel Virtualization Technology” from BIOS

Please note, when I used backup Ubuntu, it works fine. My host system is Ubuntu 18.04.3 LTS. VirtualBox Version 6.0.12, Ubuntu guest OS in VirtualBox is 18.04.2.

I will appreciate if you can help to address the issue