looks like your hard drive was damaged for some reason.
I recommend re-installing the operating system but first make sure that your harddrive can be formatted to working condition.
For Dell laptops, shut down the machine, hold the Function key (Fn) and power the laptop on. Your laptop should route to hard drive diagnostic screen. If that didnt bring you to the diagnostics then follow the step below.
Shut down the computer, turn it on, hit F12 when you see the Dell sign and choose Diagnostics from the menu.
Run harddrive diagnostics on your harddrive and see if you get any errors, if any is found, look forhelp in backing up your files before rebuilding your machine.