Keep excel cell format as text with "date like" data

try this

ws.Cell(rowCounter, colCounter).SetValue<string>(Convert.ToString(fieldValue));

c# asp.net excel closedxml

Not sure about from ClosedXML, but maybe try Range.NumberFormat (MSDN Link)

For example...

Range("A1").NumberFormat = "@"

Selection.NumberFormat = "#/####"

c# asp.net excel closedxml

Consider:

tableRow.Cell(1).Value = "'2/1997";

Note the single quote.

CodeHunter