Ajay, if you have forgotten your hall ticket number and the registration number for an examination, then you should contact the examination helpdesk of that examination as soon as possible, whose details you would get on the official website of the exam conducting authority or if you have any brochure about the exam, it would surely contain the help desk details, so contact it as soon as possible. Also, many of the authorities send these details to the e-mail id or phone number registered, so please check them for any assistance. Also, if the examination portal allows for any facility of regenerating the registration number (which is very difficult in most cases) by entering the registered e-mail id or phone number, then you should try for it to get any help.