You want to start the Virtual Machine from the VirtualBox but getting below error,
Failed to open a session for the virtual machine xxx
VM cannot start because the saved stated file yyy is invalid (VERR_FILE_NOT_FOUND).
Delete the saved state prior starting the VM
On the Oracle VM VirtualBox Manager, click on Machine > Discard Saved State (CTRL + J). Click Discard.
You can now start the Virtual Machine as usual.