Hard Drive

Is it an internal or external hard drive? Also is it plugged in properly?

I'm sorry I forgot that!!!
It is an internal hard drive. ST3500320AS
I have wo installed. 1 for the OS and 1 for storage.
The 1st went missing Friday. The 2nd OS went missing today early this morning.
I Unpluged the unit for about 4 hours and the 2nd drive with the OS came back but the other drive is stil MIA.

Sorry for miss-spelling. I am what they cal legally blind.

What is wo?

Also, turn off the computer and plug the drives in a different port.

That was meant to read two ( 2 ) of the same drives. 1st drive has my OP system on it and the 2nd is used for storage. it all started this past Friday. I mis-spoke earlier. They both went out Friday. I could not find either in the device manager or the BIOS. After unpluging it for several hours the OP system drive came back but the storage drive is still not in the device manager or the BIOS. I wondering if the hard drive has failed or if it is some where and just not coming up. I am disabled and have taken a sleeping pill and I am going to bed now. I appreciate any and all help you can provide. I have never had a hard drive to fail before so I don't know what is going on. I am tired. I have fooled with this for several days and decided to see if I could get some help from people who know their stuff. Thank You.

wo is two

 

you were faster.

So did you check the power and data cables to the hard drives if they are seated properly in both the hard drives' and the motherboard's connectors? If they are, you should check if the drive powers up at all (put your hand on it and feel if it starts resonating). Can you hear strange clicks.

I just realized that when it comes to faulty hard drives, your senses other than vision are the ones which come handy  

If nothing is strange about the disk, it still can be the cables' or the motherboard's fault (not likely, but cannot be excluded). I would try it out in another computer, or in an external USB enclosure.
Hmm... actually, the fact that at first they went missing together, doesn't make it likely that the drives are wrong. What are the chances that two drives go wrong at the very same moment...

Yes wo is two. I mistyped. I am leggaly blind. Please excuse me?

When you wake up. Try using different ports/plugs, meaning don't use the same ports/plugs the hard drives were originally on. Also make sure the plugs are not loose.

It is also possible the hard drives may have failed.

It is very unlikely that two drives failed together.

Verify that the drives work by temporarily installing and testing them in another computer.

Do not try to boot. Just install each one as another data drive. Then check that the BIOS and OS can see them.

Thanks!!! I will have to wait until someone drops by and can do this for me.
I don't know when that's going to be. But I do appreciate your help.