It is essential to defragment your hard disk on a regular basis. This is because fragmented data causes your hard drive to operate inefficiently, and can significantly slow down your system. The Disk Defragmenter is a tool designed to re-arrange all this fragmented data, enabling your hard disk to operate more efficiently. While the Defragmenter is programmed to run automatically, you can also manually defragment your hard drive.
Step1
Click on the Start button and then " All Programs." Click on "Accessories " and then click " System Tools." Step2
Click on "Disk Defragmenter," to open this utility. Enter an administrator password or give confirmation if you are prompted to. Step3
Click on " Defragment Now" which will initiate the process. Epending on the size of your hard disk and the degree of fragmentation, this process may take several minutes and a few hours to complete. 
