First how did you compress these? Winzip or with the built in window utility?
Can you explain exactly what you did ?
When it refers to a volume it means the partition on your hard drive., or in some cases it can refer to a compressed folder, meaning that you need to create a new folder on your hard drive and "extract" the files you want from the compressed folder.
What format is the compressed folder saved in?
Compressing music files really is unlikely to save you much space as they are already in a compressed format and further manipulation in an attempt to save space can corrupt them and render them useless.
IT is far better to just buy a new drive or burn files you do not use frequently to CD Or DVD.
Did you choose to "compress your drive" as a whole in order to try to save space?
Or did you right click on the folder and choose Properties =>Compress to save disk space?
Or did you right click the drive and choose properties => Compress drive to save space.
Both of these options are really not advisable. They are leftovers from the old days when Bill Gates said he did not see any reason why anyone would ever want a computer with a hard drive larger than 504MB and that 8MB of SIMM Memory would be more than adequate for whatever computers would ever be built. He later realized this was a mistake and Microsoft developed a new version of windows and manufactures came out with larger hard drives, SDRAM and eventually DDR in very large modules. It is not uncommon now to have more RAM in your computer than the size of the entire hard drive storage of early computers.
In fact most versions of windows now really require it.
So it is not advisable to use these leftover features.
The one exception is the "compress old files" in disk cleanup on NTFS formatted drives. Here it takes a bunch of files and folders which have not been accessed in a very long time and combines them into a single file which will take up far less disk space.
Some reading
http://ask-leo.com/should_i_use_wind...mpression.html