My dell Laptop Inspiron 14 (3421) making 8 beeps sound

Dear Sir,

Please help me i have bought a DELL LAPTOP inspiron 14 model 3421 some months ago, My Service Tag: <ADMIN NOTE: Service tag removed per privacy policy> | Express Service Code: <ADMIN NOTE: Express service code removed per privacy policy>, my laptop making 8 sounds beeps for last some months, i have also send it to service center as i have warranty of the products for 2 times but every times they changed my KEY BORD, still the laptop making sounds, but the problem is the sounds not happen everytime, it happen sometimes so everybody is confused whats wrong, but i noticed the laptop making 8 beeps loud sounds, But their is no problem with the LCD as i am useing the laptop finely, then why the 8 beeps happing??? today i run a diagnosis of laptop and found ERROR code: 2000-0142 validation 109906 MSG: Hard Drive 0/S/N W3POKLY0,LONG TEST UNSUCCESFULL. please help me what should i do?