Why you are using row.Cells[row.Index]. You need to specify index of column you want to search (Problem #2). For example, you need to change row.Cells[row.Index] to row.Cells[2] where 2 is index of your column:
private void btnSearch_Click(object sender, EventArgs e)
{
string searchValue = textBox1.Text;
dgvProjects.SelectionMode = DataGridViewSelectionMode.FullRowSelect;
try
{
foreach (DataGridViewRow row in dgvProjects.Rows)
{
if (row.Cells[2].Value.ToString().Equals(searchValue))
{
row.Selected = true;
break;
}
}
}
catch (Exception exc)
{
MessageBox.Show(exc.Message);
}
}