Unable to boot Dell Aspire core i7 laptop

Hello,

My dell laptop ispire core i7 is not switching on but the dell logo comes up on the screen. I tried switching it on three times but it just froze there with the logo. I tried the last time pressing F8 while starting it then it went to a window with main exit boot etc. Now I tried it again the dell logo comes up and below it words’Preparing Automatic Repair’ and it is still thinking I meaning five dots going round and round no reboot.
Please help