I have a Dell XPS 8500, with Windows 7 Professional, SP1,
with Spywareblaster, Malwarebytes, Avast , Windows Defender
and Windows firewall.

(1) TB HD
Intel (R) Core (TM) i7-33-3770 CPU @ 3.40 GHz
Ram 12.0 GB
System type : 64-bit operating system

I also have

I have a Dell Optiplex 780 Tower, with Windows 7 Professional,
SP1, with Spywareblaster, Malwarebytes, Avast , Windows Defender
and Windows firewall.

Intel (R) Core 2 Duo 2.93 GHz
4GB RAM, 750 GB HD
System type : 64-bit operating system

and (external hard drives)

Seagate Backup Plus 1(TB) 2.5 USB Portable HD

WD BLACK SERIES WD2003FZEX 2TB 7200
RPM 64MB Cache SATA 6.0Gb/s 3.5" Internal
Hard Drive

The issue involves the Dell 780. I smacked my knee against it
and when I went to power it up it beeped like(5)times and out of
1,2,3,4 lights only 3,4 appear.

So is my HD gone? or how do I resolve the problem?

Thoughts, suggestions?
Robert