SOLVED: cannot install guest OS

[jojopara]

Hello,

I had VB and Win 8.1 installed in it both running smoothly. I have no idea what happened, but there were gone.

Ever since then, I have been trying to install them back to no avail. These is what error messages I receive:
'The virtual machine 'Win 8.1' has terminated unexpectedly during startup with exit code 1 (0x1).

'Failed to open a session for the virtual machine Win 8.1.

Result Code:
NS_ERROR_FAILURE (0x80004005)
Component:
MachineWrap
Interface:
IMachine {f30138d4-e5ea-4b3a-8858-a059de4c93fd}'

I even re-installed Linux Mint Cinnamon Rosa.

Please, help.

Thank you in advance!

[mpack]

Please post a VM log file. With the VM fully shut down, right click it in GUI. Select "Show Log" and save "VBox.log" (ONLY) to a zip file. Attach the zip here.

[jojopara]

mpack, thank you for the prompt reply. I am on Limux and right -clicking does not behave as on Windows. There is no log file from VB on my machine.

[jojopara]

The trouble might be that I have forgotton how to install it although I have watched several videos. Attached is my Storage section.