Try following code to access image from a any location on your system:
private void pictureBox1_MouseClick(object sender, MouseEventArgs e)
{
OpenFileDialog ofDlg = new OpenFileDialog();
ofDlg.Filter = "Image files (.jpg, .jpeg, .bmp, .gif)|*.jpg;*.jpeg;*.bmp;*.gif";
if (ofDlg.ShowDialog() == DialogResult.OK)
{
imageFileName = ofDlg.FileName;
pictureBox1.Image = Image.FromFile(imageFileName);
}
}
Hope this will help you.