I would change a small part of your code from
dataGridview1.DataSource = ds;
to
dataGridView1.DataSource = ds.Tables[0]
UPDATE:
string TableName = comboBox1.Text;
string Query = "Select * from " + TableName;
DataSet ds = new DataSet();
using(SqlConnection connection = new SqlConnection(@"Data Source=(LocalDB)\v11.0;AttachDbFilename=C:\Users\Downloads\charityah.mdf;Integrated Security=True"))
{
SqlDataAdapter da = new SqlDataAdapater();
da.SelectCommand = new SqlCommand(Query, connection);
da.fill(ds, TableName);
}
DataGridview1.DataSource = ds.Tables[0];