C# - Saving a DataGridView to file and loading

Bind the DataGridView to a DataTable, and use the DataTable ReadXml() and WriteXml() methods to read and write the data to a file.

If you ever have multiple grids bound to multiple related tables, you can represent the schema with a DataSet and use the ReadXml() and WriteXml() methods of DataSet to read and write the whole schema.

There is an example on the MSDN page for DataTable.WriteXml() that you might find helpful.

I have tested a simple way to save datagridview to a file :

//DataGridView dgv=...
string file= "c:\\mygrid.bin";
using (BinaryWriter bw = new BinaryWriter(File.Open(file, FileMode.Create)))
{
    bw.Write(dgv.Columns.Count);
    bw.Write(dgv.Rows.Count);
    foreach (DataGridViewRow dgvR in dgv.Rows)
    {
       for (int j = 0; j < dgv.Columns.Count; ++j)
       {
           object val=dgvR.Cells[j].Value;
           if (val == null)
           {
                bw.Write(false);
                bw.Write(false);
            }
            else
            {
                bw.Write(true);
                bw.Write(val.ToString());
             }
         }
    }

and for loading such a file into a datagridview:

//DataGridView dgv = ...
dgv.Rows.Clear();
string file="c:\\mygrid.bin";
using (BinaryReader bw = new BinaryReader(File.Open(file, FileMode.Open)))
{
   int n=bw.ReadInt32();
   int m=bw.ReadInt32();
   for(int i=0;i<m;++i)
   {
         dgv.Rows.Add();
         for (int j = 0; j < n; ++j)
         {
               if (bw.ReadBoolean())
               {                                        
                     dgv.Rows[i].Cells[j].Value = bw.ReadString();                                        
               }
               else bw.ReadBoolean();
          }
     }
} 

Consider that I have assumed that the datagridview control has fixed columns, in you specific situation you should add some codes to insert new columns or create a new gridview.