check this solution
using excel = Microsoft.Office.Interop.Excel;
excel.Application eApp = new excel.Application();
excel.Worksheet eWsheet = new excel.Worksheet();
excel.Workbook eWbook;
eWbook = (excel.Workbook)(eApp.Workbooks.Add(@"C:\abc.xls"));
eWsheet = (excel.Worksheet)eWbook.Worksheets[1];
eWsheet.get_Range("A4", "A4").NumberFormat = "@";
code in vb.net
Imports excel = Microsoft.Office.Interop.Excel
Dim eApp As excel.Application = New excel.Application()
Dim eWsheet As excel.Worksheet = New excel.Worksheet()
Dim eWbook As excel.Workbook
eWbook = CType((eApp.Workbooks.Add("C:\abc.xls")), excel.Workbook)
eWsheet = CType(eWbook.Worksheets(1), excel.Worksheet)
eWsheet.get_Range("A4", "A4").NumberFormat = ""