The damaged internal code that is printed out,

Data[{ Cell[20901203, 381552, 112, 1, 41, "Subsection"], Cell[CellGroupData[{ Cell[20901340, 381557, 902, 23, 52, "Input"],

comes from the bottom of the notebook file and might not be necessary. Try opening the notebook with

• File menu - Open,
• select the notebook to open (click once),
• click the OPTIONS button in the bottom of the dialog,
• in the Notebook Options window, click the checkbox in front of Parse and load entire notebook on opening,
• click OK to close the Notebook Options window, and
• click Open.

See the attached screen shot. (This does not read in the entire notebook, just the parts needed for the code and formatting and without some metadata at the bottom.)

Instead of choosing the "yes" (to plain text) from Mathematica's environment, try to open the notebook filename.nb from a text editor like TextEdit (or somesuch).

• Option 1: If the file exists and opens, you can copy and paste your data (just the numbers) into another notebook if it's a small list.
• Option 2:
• (a) Visually and (from testing your error in Mma 7, you may be missing closing braces and square brackets. Insert them and try to reopen in Mma.
• (b) I don't think the Data[{..... should be there unless its a valid object that i don't have in Mma 7. You can try to delete the Data[{... and try reopen.

Thank you.