In order to see the closed sprints not displayed on the Sprint Scheduling page, please do the following:
Go to the Sprint Scheduling Page:
You will then be taken to the Sprint Schedule details page and here you can find the older sprints.
Re-opening an Older Sprint –
When you get to the list of the older closed Sprints, if you click on the link to one of the old ones, it will open up a box like the one below. From there you should be able to click on the blank drop down to the right of the screen and choose reopen sprint.