Unfortunately, you cannot restore a deleted Learning Plan. However, deleting a Learning Plan does not have any effect on your staffs progress through the content that was in the deleted Learning Plan. If you set up a new Learning Plan, identical to the one you deleted, you'll be able to run the same reports on the Learning Plan and everyone's previous progress will remain unchanged.
Alternatively, you can go to Reports > User Report > Export Course Progresses to export a list of all staffs completed and in progress training