Can't change my IP address?

Usually, doing the ipconfig/release thing and then the thing in Network Connections has always worked. But it doesn't anymore, all of a sudden. Nothing has changed since the last time it worked. My IP remains the same.
Update: This is my desktop.

And I went to that place in Network Connections, but I didn't see anything about a static IP address. That's the place where I go to chance my IP after the ipconfig/release.
Update 2: I don't want to do anything too complicated. Really, I'd just like to figure out why the normal method has stopped working.
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