The problem is likely in the configuration file. If you force-shutdown your host, then the VirtualBox configuration file can get corrupted. At this point its important to *not run the VM again* before resolving the corruption, otherwise you’d lose the configuration backup that VirtualBox does automatically.

To resolve the corruption, go into the directory where your VirtualBox VMs are stored (it changes according to the user – sometimes its in Documents. If you are unsure, open the VirtualBox application, right click the VM you are having trouble with and select “Show in file manager”). There should be a “VM name”.vbox file, and there should also be a file named the same but with the extension “vbox-prev” – that file is the configuration backup that VirtualBox keeps. You need to compare the two files and fix the problems in the first. If its too much of a problem (or if the first file is too much gone), you can just copy the backup file over the current one and see if that lets you start your VM.