How do I repair a partitioned hard drive that has corrupted/loss of volume space?

sometimes Hard drives don't show all the space on that dive ex. my PC is 200GB but the hard drive says 186GB as its full Capacity the cause for this is that the dive needs this space for partitioning and formatting between drives, when a ha`rd drive is smaller like 40Gb it willshow up as 37.2GB on flash drives ex. 8GB will say 7.43GB. i would recommend you use EASUS Partition master to create partitions its very easy to us and easy to remove partitions. I HIGHLY RECOMMEND YOU MAKE A SET OF SYSTEM RESTORE CDS YOU WILL AWAYS BE ABLE TO RESTORE YOURE PC TO ITS FACTORY SETTINGS!!!!!!

you need to partition and format it first before you can use it. When you buy a new computer, you receive it ready for use, that is it's already partitioned (usually one sometimes two partition) and formatted. If you are adding new unformatted, unpartitioned Hard drive, or if you want to create a computer system that can run more then one operating systems, such as Windows XP and Linux (dual booting) - you will need to partition the hard drive yourself. Formatting destroys the data in the areas of the disk it partitions, so be sure to make a backup copy of all the information on your disk before formatting your drive or partition it. If your installing a new second hard drive then you don't need to backup the new drive, but you should consider backing-up your data on the first (master ) hard drive. Disk Management tool - To partition your new hard drive (the default is NTFS), you need to use the Disk Management tool, this is a tool straight from the old work-horse Windows 2000. To run Disk Management Tool, click on Start, right-click My Computer, and select Manage from the menu that appears. When you see the Computer Management window, click the Disk Management item listed underneath the Storage heading. You then see the main Disk Management pane in the right side of the Computer Management window. Tip: Windows XP doesn't provide a way to resize partitions later, but you can use a third-party program like PartitionMagic to do so. Tip: Before working with partitions and drives, be sure to back up the important files on your system. Note: The Disk Management program replaces the Fdisk program that was part of previous versions of Windows. Creating the partition: Unallocated space appears as an Unknown Partition in the Disk Management diagram, you can use it to create a new partition in some or all of the space. To create your new partition, you need to right-click on the part of the diagram that represents the unallocated space, the unallocated space has a black stripe running along the top and then choose the "New Partition" on the menu that appears. To create your new logical drive in an extended partition that has free space The free space has a light green strip along the top, right-click on the free space then choose New Logical Drive from the menu that appears. Now you will see the New Partition Wizard. The Partition Wizard will asks you to specify the following: 1 The Type - Primary, extended, or logical partition. Your hard drive can contain up to four primary partitions, or three primary partitions and one extended partition. Choose the primary partition if you are created a partition in which you will install an operating system (this is unusual situation). Choose extended if you plan to create several logical partitions within it. The logical partition type is available only if you choose to create the new partition in an extended partition with some free space. 2 The Size - You may use the entire available space, or leave room for more partitions. The Partition Wizard will displays the minimum and maximum size for the partition, this is based on the space where it will be stored 3 The Drive letter or path - Two operating system on your computer. You may select any unused letter, but the wizard will offer the next available drive letter. To Mount in the following empty NTFS Folder, you need an NTFS partition with a drive letter on the same machine. You may select the "Do Not Assign A Drive Letter Or Drive Path" option, this will let Windows assign a letter later, usually the default drive letter. 4 The File system - The default is NTFS (recommended), but you can use FAT32 (not recommended) as well. Both NTFS and FAT32 will efficiently utilize disk space on large drives. Note: NTFS has better security features, the better recovery capabilities after a major crash, and has file-level compression built in. NTFS will also give you the option of enable compression. 5 The Label - Type a name for the partition, name it something that will indicating what you will use it for, data files, my files, fatboy one, etc. This is the final screen of the New Partition Wizard, summarizing your choices before Windows creates the partition. Formatting a new partition can take several minutes. Selecting the Active Partition: If you partition your hard drive among multiple operating systems, one of the partitions is the active partition, the partition from which your computer starts. If you run Windows only, the primary partition is always active. In Windows XP you can change this behavior manually by selecting another partition as active using the Disk Management pane in the Computer Management window. Right-click on the drive or the partition that you want to make active and select Mark Partition As Active from the menu that appears. You can only make this change to primary partitions. Extended partitions and logical drives cannot be made active. Only one partition is active at a time, so make sure it's a partition that contains a bootable operating system!

Let me know if you're using a branded desktop/laptop if so then there would some OS and recovery files stored in a hidden partition and that would not be displayed. If you do not need those files then you can use partition magic to recover the space and extend that on one of your other drives.