Failed to open session for Virtual Machine

[viakondratiuk]

My virtual machine unexpectedly closed and now I can't start it.
I'm getting such message:

Failed to open a session for the virtual machine 12.04.

The virtual machine '12.04' has terminated unexpectedly during startup with exit code 1 (0x1). More details may be available in 'F:\VirtualBoxVMs\12.04\Logs\VBoxStartup.log'.

Result Code: E_FAIL (0x80004005)
Component: Machine
Interface: IMachine {480cf695-2d8d-4256-9c7c-cce4184fa048}

VB version is: 4.3.20

Are there any steps how I can restore it?

[mpack]

Please check for previous answers (e.g. in the posting right before yours), before posting a question.