Hello David,
Fortunately Land F/X has several levels of backups. You can find the backup file - with an .lfx extension - for this particular project in the same directory as your .dwg file.
Land F/X saves a new backup every time you save the .dwg in the same directory so it will likely be the most recent backup of the project.

Here are the steps to import the file into Land F/X:
https://www.landfx.com/index.php/docs/admin/project-management/item/1535-backup-or-restore.html#restore

I will send you a private email with re-installation information in case you need to re-install Land F/X on your new computer as well.

Thanks!