My Solution in vb.net
Dim drow As DataRow = datatable1.Select("YourColumn='" & YourValueString & "'")(0)
Dim tempIndex as integer =datatable1.Rows.IndexOf(drow)
in C#:
DataRow drow = datatable1.Select(("YourColumn=\'"
+ (YourValueString + "\'")))[0];
int tempIndex = datatable1.Rows.IndexOf(drow);