using System;

using System.Data;

using System.IO;

namespace TestTextToDataSet

{

  public class TextToDataSet

  { 

    public TextToDataSet()

    {  }

   /// <summary>

    /// Converts a given delimited file into a dataset. 

    /// Assumes that the first line    

  /// of the text file contains the column names.

  /// </summary>

    /// <param name="File">The name of the file to open</param>    

  /// <param name="TableName">The name of the 

  /// Table to be made within the DataSet returned</param>

    /// <param name="delimiter">The string to delimit by</param>

   /// <returns></returns>  

  public static DataSet Convert(string File, 

   string TableName, string delimiter)

    {   

    //The DataSet to Return

    DataSet result = new DataSet();

    //Open the file in a stream reader.

      StreamReader s = new StreamReader(File);

    //Split the first line into the columns       

     string[] columns = s.ReadLine().Split(delimiter.ToCharArray());

    //Add the new DataTable to the RecordSet

      result.Tables.Add(TableName);

    //Cycle the colums, adding those that don't exist yet 

    //and sequencing the one that do.

      foreach(string col in columns)

      {

        bool added = false;

        string next = "";

      int i = 0;

      while(!added)        

      {

        //Build the column name and remove any unwanted characters.

        string columnname = col + next;

         columnname = columnname.Replace("#","");

          columnname = columnname.Replace("'","");

          columnname = columnname.Replace("&","");

        //See if the column already exists

        if(!result.Tables[TableName].Columns.Contains(columnname))

          {

          //if it doesn't then we add it here and mark it as added

            result.Tables[TableName].Columns.Add(columnname);

            added = true;

          }

          else

        {

          //if it did exist then we increment the sequencer and try again.

            i++;  

          next = "_" + i.ToString();

          }         

      }

    }

    //Read the rest of the data in the file.        

     string AllData = s.ReadToEnd();

    //Split off each row at the Carriage Return/Line Feed

    //Default line ending in most windows exports.  

    //You may have to edit this to match your particular file.

    //This will work for Excel, Access, etc. default exports.

    string[] rows = AllData.Split("\r\n".ToCharArray());

      //Now add each row to the DataSet        

    foreach(string r in rows)

      {

      //Split the row at the delimiter.

        string[] items = r.Split(delimiter.ToCharArray());

      //Add the item

       result.Tables[TableName].Rows.Add(items);  

      }

    //Return the imported data.        

    return result;

    }

  }

 }

Source: http://www.codeproject.com/KB/database/DataSetFrmDelimTxt.aspx