After IntelliJ IDEA froze and was killed from the task manager, all the Run/Debug Configurations disappeared. I have tried invalidating caches, reloading files from disk, synchronizing and restarting, but nothing helped.
You can try to restore your Run configuration using the Local History feature of IntelliJ IDEA.
If you are using .idea directory based format, then your configurations will reside in workspace.xml file under .idea directory, invoke Local History dialog from the .idea directory right click menu in IDEA Project View, select the label some time before the crash and revert the old copy of workspace.xml.
In case .ipr file based format is used, your configurations will be stored in the <project>.iws file in the project root which you can restore in a similar way.
If the configurations were Shared, they are stored in .idea\runConfigurations directory as separate XML files or in the <project>.ipr file (if old project format is used).
If the Local history is blank and you are in Windows, try Restore previous versions right clicking the workspace.xml file or the <project>.iws one in Windows Explorer.