May be this will Help you..!!
Declare string array which coumn you want to distinct
string[] TobeDistinct = { "Cloumn1", "Cloumn2", "Cloumn3" };
call GetDistinctRecords fuction which will return you distinct record.
DataTable dtDistinct = GetDistinctRecords(dt, TobeDistinct);
Fuction is here:
private DataTable GetDistinctRecords(DataTable dt, string[] Columns)
{
DataTable dtUniqRecords = new DataTable();
dtUniqRecords = dt.DefaultView.ToTable(true, Columns);
return dtUniqRecords;
}