Hello aspirant!  First of all you must check out your email I'd , the board might have sent you a login ID and password to email account that you have registered or the SMS box in the mobile phone. If it's not their then you can go to the contact us section in the official website of Ap eamcet.  You can use the link below :

https://www.google.com/url?sa=t&source=web&rct=j&url=https://sche.ap.gov.in/EAMCET/EamcetHomePages/ContactUs.aspx&ved=2ahUKEwiHgaemoKnjAhVEQH0KHV4UAtoQFjAAegQIARAB&usg=AOvVaw2J_2HzkbPTc5HbzH2evExc&cshid=1562723947559