Error: INACCESSIBLE_BOOT_DEVICE AND Oxc000000f

I cannot login to my Dell Inspiron 15 with Windows 8.1. I need help. I do not have a recovery disc and I have tried all the 8 restart options on the blue screen. I have no idea what else to do. I am running the Pre-boot System Assessment but it keeps saying there is no problem found. I loved my laptop now all its doing is collecting dust. Please help me if you can. I think I have tried all options I can do at this point. Thanks.