It’s long been the conclusion of scholars that Esther and Nehemiah are the only books of the OT not represented among the Dead Sea Scrolls.  The May/June 2012 issue of Biblical Archaeology Review (BAR), however, reports that Norwegian scholar, Torleif Elgvin of the Evangelical Lutheran University College in Oslo, Norway, and Esther Eshel of Bar-Ilan University are publishing a collection of two dozen previously unknown DSS fragments from Cave 4, the Bar-Kokhba caves, and Wadi ed-Daliyeh in a book titled Gleanings from the Caves (T&T Clark publishers).  If this checks out, then Esther would remain the only book not found in the DSS.  Of course, if Nehemiah and Esther were written on the same scroll as most scholars believe, then while we may not have an extant copy of Esther from the DSS, there is good reason to believe the text was present in the community as part of the Nehemiah scroll.