You have created an Org structure and saved the same. But, now the structure is missing.
The reason that you are not able to view the saved org structure is that you might have used the ROLLBACK option. The Rollback option revert the org structure to last activation. So in this case, since the you haven't activated the org structure, all the creation and changes have been reverted to initial.
When you have selected the rollback button, system throws a warning message Are you sure you want to roll back all pending organizational changes? Roll back deletes all changes made to the Organizational structure, and returns to the currently active version. It deletes organizational units that have not yet activated. This action has system-wide consequences and also affects org structure and units that are not currently shown on the screen. This action cannot be undone. To roll back click OK. To return to the previous screen click Cancel. If you clicked OK the action is triggered.
So in this case, it is not possible to undone the roll back which means the structure needs to rebuild.
If you have not used the Rollback option, then you can refer the Knowledge Base document: 1627660 - Newly Created Org Structure is not Displaying in the Planning Area
KBA , SRD-MD-OM , Organizational Management , How To