How do I restore sub-tasks that have disappeared after migrating Jira issues between projects?

[Oliver Chambers]

I recently moved a few hundred Jira issues from one project to another - including stories, tasks and bugs.  

The sub-tasks have disappeared.

I received the following warning when migrating:

'Please note that 81 sub-task issues were removed from the selection and do not appear in the table below.  You are not allowed to bulk move sub-task issues together with their parent issue.  In this case, you will only be asked to move the sub-task if you move the parent issue to anew project'.

I stupidly made the assumption the sub-tasks would remain in the original project, but I can't see them anywhere.

Thanks,

Ollie.

[Hamid Pajouhandeh]

Not sure if you already found the solution, but I think JIRA will keep the history and sub-tasks links to the parents.
(I just stumbled upon this post. Responding just in case anyone else finds the below useful. 6 years later, but better late than never, I say)

By running this query from Filters you should be able to find the disappeared sub-tasks:

issuetype = sub-task and parent in (enter the parent keys)