The blank back error is so severe that it is almost boring. This misprint is a result of the back of any bill completely missing its printing.
Blank back misprints are fairly common. A note that does not have a back should be worth around $300 in nice condition. If the note is perfect it could be worth more, if the note is heavily circulated then it will be worth less.
The back printing on bill can be chemically removed. If your bills has a slight yellow color to the back of it, then it was probably chemically altered.