DataTable Creation

    public class DataTableHelper
    {
        /// 

        /// To Create Table Skeleton.
        /// 
        /// Table Column Name as an Array/// Column DataType as an Array/// Name of the DataTable/// 
        public DataTable CreateDataTable(string[] ColumnName, string[] DataType, string TableName)
        {
            // Create DataTable.   
            DataTable table = new DataTable(TableName);
            try
            {
                for (int i = 0; i < ColumnName.Length; i++)
                {
                    // Create DataColumns and add them to DataTable.   
                    table.Columns.Add(CreateDataColumn(DataType[i].Trim(), ColumnName[i].Trim(), "Column", false, false, false));
                }
            }
            catch (Exception)
            {
            }
            return table;
        }

        /// 

        /// To create the table structure
        /// 
        /// Column DataType/// ColumnName/// Column Caption/// Is Auto Increament/// IsReadOnly/// /// 
        private DataColumn CreateDataColumn(string colType, string name, string caption, bool autoInc, bool readOnly, bool unique)
        {
            DataColumn column = new DataColumn();
            try
            {
                column.DataType = System.Type.GetType(colType);
                column.ColumnName = name;
                column.Caption = caption;
                column.AutoIncrement = autoInc;
                column.ReadOnly = readOnly;
                column.Unique = unique;
            }
            catch (Exception)
            {
            }

            return column;
        }

        /// 

        /// Add Row to a DataTable
        /// //How to Call?
        /// //tempDt = oblDataTableHelper.AddRowsToTable(strArrField, tempDt);
        /// 
        /// Column Data as String Array/// Name of DataTable to add the Row/// 
        public DataTable AddRowsToTable(string[] value, DataTable table)
        {
            // Generate row with values for each column.   
            DataRow row = table.NewRow();
            try
            {
                //Add values to the columns
                for (int i = 0; i < value.Length; i++)
                    row[i] = value[i];

                // Add row to table.   
                table.Rows.Add(row);
            }
            catch (Exception)
            {
            }

            return table;
        }

        /// 

        /// Check whether the table contains Duplicate value for a particular column
        /// 
        /// DataTable/// Name of Column to Check for Duplicate/// 
        public bool HasDuplicates(DataTable table, string columnName)
        {
            bool IsContainsDuplicates = false;
            try
            {
                Hashtable hTable = new Hashtable();

                foreach (DataRow row in table.Rows)
                    if (!hTable.Contains(row[columnName]))
                        hTable.Add(row[columnName], null);
                    else
                    {
                        IsContainsDuplicates = true;
                        break;
                    }
            }
            catch (Exception)
            {
            }

            return IsContainsDuplicates;
        }

        /// 

        /// Remove rows for certains columns contains duplicate value
        /// //How to Call?
        /// tempDt = oblDataTableHelper.RemoveDuplicateRows(tempDt, new System.Collections.Generic.List(ColumnName));
        /// 
        /// DataTable Instance/// ColumnName as List/// 
        public DataTable RemoveDuplicateRows(DataTable table, List keyColumns)
        {
            //DataTable results = myDataTable.AsEnumerable().Distinct().CopyToDataTable();

            DataTable duplicateTable = table.Clone();
            DataColumn[] primaryKey = new DataColumn[duplicateTable.Columns.Count];
            duplicateTable.Columns.CopyTo(primaryKey, 0);
            duplicateTable.PrimaryKey = primaryKey;

            DataRow[] dataRows = new DataRow[table.Rows.Count];
            table.Rows.CopyTo(dataRows, 0);
            foreach (DataRow dataRow in dataRows)
                if (duplicateTable.Rows.Contains(dataRow.ItemArray))
                    table.Rows.Remove(dataRow);
                else
                    duplicateTable.Rows.Add(dataRow.ItemArray);

            return table;
        }

        //tempDt = oblDataTableHelper.RemoveDuplicateRows(tempDt, ColumnName);
        /// 

        /// Remove rows for certains columns contains duplicate value
        /// 
        /// DataTable Instance/// ColumnName as Array/// 
        public DataTable RemoveDuplicateRows(DataTable dTable, string[] strColumns)
        {
            // create a dv from the source dt 
            DataView dv = new DataView(dTable);
            // set the output columns array of the destination dt 
            // true = yes, i need distinct values. 
            return dv.ToTable(true, strColumns);
        }
    }

Calling The Function

DataTableHelper oblDataTableHelper = new DataTableHelper();
string[] ColumnName = new string[] { "Column1", "Column2", "Column3", "Column4" };
string[] DataType = new string[] { "System.String", "System.String", "System.String", "System.String" };
System.Data.DataTable tempDt = null;
tempDt = oblDataTableHelper.CreateDataTable(ColumnName, DataType, "DataTableName");

Path that gives me the idea

Failed to load viewstate. The control tree into which viewstate is being loaded must match the control tree that was used to save viewstate during

Failed to load viewstate.
match the control tree that was used to save viewstate
during the previous request. For example, when adding
controls dynamically, the controls added during a
post-back must match the type and position of the
controls added during the initial request.

This occurs in when press the command field(Edit button) 
in the gridview.

To solve we have to bind the GridView once again.

 
protected void GridView1_RowEditing(object sender, 
System.Web.UI.WebControls.GridViewEditEventArgs e)
{
    GridView1.EditIndex = e.NewEditIndex;
    BindGrid();
}