No Problem as we all here will help you.
give a try on following, replace the datatavar with your variablename:
(From r In DataTableVar.AsEnumerable
Select ia = r.ItemArray.toList
Select ic = ia.ConvertAll(Function (e) e.ToString.Replace(“A”, “YourReplacementValue”).toArray()
the text replace approach is also a good option for solving the task. And for beginning doing the replacement with for each row and an inner for each iteration over the columns should work as well
Let us know if you do need more help. Feel free to share some sample data with us