You have to change Source page code here..
onpageindexchanging = "GridView2_PageIndexChanging" to
OnPageIndexChanging = "GridView2_PageIndexChanging"
protected void Recentinternship()
{
SqlConnection con = new SqlConnection("Data Source=jayraj-pc\\sqlexpress;Initial Catalog=Internship;Integrated Security=True;Pooling=False");
con.Open();
string str = "select B.CompanyLogo as ' ',A.Title,A.InternshipStartDate,A.ApplicationDeadline,A.Duration,A.InternshipCity,A.Category,A.Stipend,A.InternshipID,A.Degree,A.Branch,A.CompanyID,A.Title,A.CompanyName from Internship AS A INNER JOIN Companies AS B ON A.CompanyID=B.CompanyID ";
SqlDataAdapter da = new SqlDataAdapter(str,con);
DataSet ds = new DataSet();
da.fill(ds,"0");
GridView2.DataSource = ds.Tables["0"].ToString();
GridView2.DataBind();
dr.Close();
con.Close();
}