The sidebar on my windows are gone.How do I get it back?

I no longer have the blue part on the side that have the drop down lists like: "File and Folder tasks" or "other places",or "Details".

I tried linking a picture of what I'm talking about, but it seems I'm unable too due to being a new user.I hope someone here knows what I'm talking about without the picture, because I don't know how else to explain it.Thank you.