If you've accidentally archived your requisition prior to it being approved or rejected, you can unarchive it.
Unarchiving a Requisition
To unarchive a requisition:
Expand Jobs.
Select Requisitions.
Go to the Archived tab.
Click the three-dot menu (⋯) icon to the right of the requisition.
Select Unarchive.
Your requisition will move back to the Open tab.