Server Error in '/' Application. The resource cannot be found error in asp.net -

Server Error in '/' Application. The resource cannot be found error in asp.net -

resource not found error while trying send url of alter password registered email. have checked spelling , directories of project. fine still getting error. url sending email registered users.

sbemailbody.append("http://localhost/virtualclassroom/register/changepassword.aspx?uid=" + uniqueid);

when click link,i getting error.i new .net.please help.thanks in advance!

asp.net