Cannot find a destination volume

BDAqua, thank you for your response.

While in the First Aid tab with the disk selected, I am not able to select "Repair Disk" because it is darkened.

Also, when I run the command "ps aux", a few lines of stuff shows up.

On the Apple Support article, it says that there may be a delay in the disk showing up because it has to first be checked, and the larger the volume, the longer it will take to check. I was using this disk and it had a large amount of data on it, but I have waited for 1-2 hours and it still did not show up. Any other suggestions or thoughts as to what is going on or what I can try?

Thanks

When I held CMD+s during bootup, the Mac ejected the CD-ROM. This was the disk that I was using.

The Mac then displayed the flashing folder with the "?" on it. So I inserted my Snow Leopard installation disk. I still had the same problem in Disk Utility. I turned off the machine and held down the CMD+s. I went into single user mode and entered the code. When I did that, it gave me the message "The volume Mac OS X Install DVD appears to be OK."

I then went to Disc Utility and looked at a partition of the disk. It is a 500 GB disk, but it let me create 1 partition at 250 GB. I then went to the Select Destination Window, and the partition that I had created, named "Untitled" was there. But this is only for 250 GB and the HD is 500 Gb. Is there a part of the disc that is not being recognized? I am currently installing the Snow Leopard on the partition.

I went to SU and did the cd /volumes/

ls -a

and the response was "Untitled" which is what I named the disk. Perhaps I installed a 250 GB HD, but my order history in Amazon shows a 500GB. Is there any other way to tell other than pulling the HD out and looking at it?