Please see this article on repairing corrupted notebooks.
http://support.wolfram.com/kb/3300
If this doesn't work try to evaluate the following code:
RecreateNotebook[fileName_String]:=
Module[{nb=NotebookCreate[],strm=OpenRead[fileName,BinaryFormat->True],result,cell,tmpChar,beginPos,endPos},
While[(result=Find[strm,{"Cell[\"","Cell[BoxData[","Cell[TextData["}])=!=EndOfFile,
beginPos=SetStreamPosition[strm,StreamPosition-StringLength[result]];
Quiet[cell=Check[Read[strm,Expression],tmpChar=" ";endPos=StreamPosition;
While[tmpChar=!=","&&endPos>beginPos+1,SetStreamPosition[strm,--endPos];
tmpChar=Read[strm,Character]]; If[endPos>beginPos,SetStreamPosition[strm,beginPos];
ToExpression@StringJoin@ReadList[strm,Character,endPos-beginPos],$Failed]]];
If[Head[cell]===Cell,NotebookWrite[nb,cell,After]];];Close;]
Then run the function RecreateNotebook on the file path to the corrupted file.
You can use Insert > FilePath... to insert the file path into the notebook.
If you still see any issues, contact Wolfram Technical Support at support@wolfram.com with your name and license number or activation key.
