You likely have a hard drive failure, as the magnetic material on the first eight sectors sometimes bubbles up and flakes away as the drive ages. You may still be able to save the data using an external USB drive, but you will need to install a new drive, and use your Dell disk set to reinstall Windows, drivers, etc... then you have the other software to worry about unless you have the install disk.
A good external USB enclosure with its own power supply will allow you to examine the contents of the drive, and to copy files to another drive, but it will not enable a boot.