I want to search data from datagridview by search text box double click the result to fill the textboxes in parent form

Question

I'm working on windows form application using C# .NET framework 4.8

Someone implemented code experience answer this.

Error System.NullReferenceException: 'Object reference not set to an instance of an object.'

(dgvRegistration.DataSource as DataTable).DefaultView.RowFilter = 
   string.Format("RegID='{0}'",txtSearch.Text);

Error: System.NullReferenceException: 'Object reference not set to an instance of an object.'

DataTable dataTable = (dgvRegistration.DataSource as DataTable);
dataTable.DefaultView.RowFilter = string.Format("RegID LIKE '{0}%'", txtSearch.Text);

Error: System.InvalidCastException: 'Unable to cast object of type 'System.Data.DataView' to type 'System.Data.DataSet'.'

DataSet dataSet = (DataSet)dgvRegistration.DataSource;
DataTable dt = ((DataView)dgvRegistration.DataSource).Table;
dt.DefaultView.RowFilter = string.Format("RegID LIKE '{0}%'", txtSearch.Text);
dataSet = (DataSet)(dgvRegistration.DataSource);

dgvRegistration.Refresh();

I want to search data from DataGridView by search text box, double click the result to fill the textboxes in parent form.

Also I can search any thing or any data like a dynamic search from DataGridView control.