Anastasia,
As Rodney said that controller has been flooded and is badly rusted.
At the least it will need to be cleaned thoroughly inside the ceramic shell ( white part ) as well as the metal parts.
I probably is fixable, just take your time with it.
Test it first to see if it works and if it does give it a shot.
There isn't really a need for an underwriters knot on these. The way the body parts are made puts a kink on the cord and holds it but if you want to put one in it won't hurt.
Joe