My Dell Latitude e6420 can't boot up

I was working on my laptop mistakenly I disconnected the power cable, and since my battery is dead, laptop went off. When I powered it on it showed can't read disk error, press Ctrl ALt Del. I tried that but didn't work, so I changed the BIOS info to default. When I tried to reboot, it's now showing me incorrect configuration message and requires me to run set-up, I am now on boot sequence but I can't figure out what to do, help