notebooks - How can I recover the source code from cdf file?

by a mistake I have deleted the nb file by which the CDF was generated.

All required definitions were in one cell. If I remember the code looked like this:

Grid[{{Button[..],..}, 
  Dynamic[ ParametricPlot[..,Initialization:>{functions definitions}]]]

and later I selected the output cell and saved the selection by: File > CDF Export > Standalone.

I can open the CDF in a text editor but it is highly unreadable and is difficult to extract all the math commands.

Answer

Edit with a more compact code:

CellPrint @ Cell[
  BoxData[
    StringReplace["$CellContext`" -> ""] @ ToString[ 
      ToExpression @ Get[pathToYourCDF][[1, 1, 1, 1]]
    , InputForm
    ] 

  ]
, "Input"
]

Old answer:

Open your cdf in Mathematica. Then open new Notebook and evaluate:

Select[Notebooks[], ("DocumentType" /. NotebookInformation[#]) =="CDF" &
      ][[ 1]] // NotebookGet // NotebookWrite[EvaluationNotebook[], #[[ 1]]] &

SelectionMove[EvaluationNotebook[], Previous, CellContents]


NotebookApply[EvaluationNotebook[], 
              RowBox[{"InputForm", "[", "\[SelectionPlaceholder]", "]"}]]

SelectionMove[EvaluationNotebook[], All, CellContents]

SelectionEvaluate[EvaluationNotebook[]]