Change this:
MySqlCommand sqlcom = new MySqlCommand("UPDATE t_company SET Company_Name=@Company_Name,Description=@Description,Email=@Email where Company_Name=@Company_Name'" + "'", mycon1);
to this:
MySqlCommand sqlcom = new MySqlCommand("UPDATE t_company SET Company_Name=@Company_Name,Description=@Description,Email=@Email where Company_Name=@Company_Name", mycon1);
i.e. remove the extra quotes that you were appending. Parameterisation in ADO.NET takes care of putting the right quotes for you automatically.
also get rid of:
sqlcom.Connection = mycon1;
as you have already specified it in your MySqlCommand constructor.