Chkdsk (an acronym for check disk) is a Microsoft® utility designed to check the integrity of the data on a computer's hard disk drive as well as find and fix errors which could muddle data. On computers using Windows® XP and 2000, chkdsk is essentially a replacement for scandisk which was used on Windows® '95, '98 and ME versions. Running chkdsk on computers with Windows Vista or  Windows 7 is somewhat different, but provides the same benefits.

Running chkdsk on your Windows® XP or 2000 system can most often repair numerous minor Windows® problems you may have experienced and/or encountered. Many people regularly run chkdsk as a part of their overall computer maintenance plan. To stop an already scheduled chkdsk operation you must edit the registry using Registry Editor and this can be dangerous if you are not familiar with using the Registry Editor because, if you edit it  incorrectly, it can can cause disastrous, system wide problems.

Chkdsk harkens back to the days of MS-DOS and one can only wonder exactly why Microsoft® chose to revert to its use because it is, quite frankly, a little clunky, however, well worth the time and effort. There are several different methods that can be used to run chkdsk on a Windows® XP or 2000 machine but the most basic is as follows:

1. Click the Start button then select Run
2. In the Run window's Open box, type cmd or command
3. Click OK and an MS-DOS-style black screen will appear in a new window
4. Run chkdsk by typing one of the the following commands where the cursor is blinking:
a. chkdsk c: /f /r  and then press <Enter> (see Notes below)
OR
b. chkdsk c: /f  and then press <Enter> (see Notes below)
5. With either command, a message will appear that says: "chkdsk cannot run because the volume is in use by another process. Would you like to schedule this volume to be checked the next time the system restarts? <y/n>"
6. Type y (for "yes") and then press <Enter> Caution: canceling an already scheduled chkdsk is a giant hassle so be sure you want to run chkdsk before completing this step. For information about how to cancel an already scheduled chkdsk, visit Microsoft® at: https://support.microsoft.com/kb/158675
7. A message will appear that will say: "This volume will be checked the next time the system restarts"
8. Type exit and then press <Enter> to close the MS-DOS-style black screen window
9. Reboot (restart) the computer as you normally would and chkdsk will automatically begin running after your reboot (restart). While chkdsk is running, you will see a light blue window with a dark blue band at the top and bottom. Chkdsk will display the specific stage it is checking as well as the percentage of completion of the stage. You cannot do anything else on your computer while chkdsk is running. When chkdsk is finished, it will automatically reboot (restart) your computer.

For more information about chkdsk, visit the Microsoft® site at: https://www.microsoft.com/resources/documentation/windows/xp/all/proddocs/en-us/chkdsk.mspx

Notes:
Typing chkdsk c: /f (as in 4b above) will only fix errors that are encountered, while typing chkdsk c: /f /r (as in 4a above) will both fix errors and recover lost data. Running chkdsk with both the /f and /r options (as in 4a above) can often take a considerable amount of time—depending upon the size of your hard drive and the amount of data stored on it. For example, a 60GB hard drive with about half the drive filled with data will take about an hour and fifteen minutes when you use both the /f  and /r options.

The exact amount of time it takes to run chkdsk with both the /f and /r options (as in 4a above) varies from one computer to another because it is dependent upon both the physical size of the hard drive as well as the amount of data stored on it. As a very general rule of thumb, it will probably take at least as long to run chkdsk with both the /f and /r options as it does to accomplish a full and complete virus scan of your computer. In any case, be prepared to take a long lunch because waiting for chkdskto finish is somewhat akin to watching paint dry.

While running chkdsk with only the /f option (as in 4b above) is faster, it will only fix errors, not recover any lost data. However, using only the /f option on, for example, a 60GB hard drive with about half the drive filled with data will only take about twenty minutes.

While chkdsk is running you willl see a light blue screen with a dark blue border at the top and bottom of the screen. At the top right side of the screen you will see the Windows logo and "Microsoft Windows" displayed.

chkdsk will run through 5 different stages and display a notification of each stage as it is being performed:

Verifying Files (Stage 1 of 5)
Verifying Indexes (Stage 2 of 5)
Verifying Security Descriptors (Stage 3 of 5)
          you may also see "Verifying Usn Journal ..." at this point before stage 4 commences
Verifying File Data (Stage 4 of 5)
Verifying Free Space (Stage 5 of 5)

While chkdsk is running through each stage, it will display a "x percent completed" notice immediately beneath the stage description. Stages 4 and 5 will take the most time. At times, you may see a "100 percent completed" notice and the program will just "hang." Be patient. It sometimes takes a while for the next stage to begin.

Canceling a Scheduled chkdsk operation:
WARNING — To stop an already scheduled chkdsk operation you must edit the registry using Registry Editor. This can prove to be dangerous if you are not familiar with using the Registry Editor. Using Registry Editor incorrectly can cause disastrous, system wide problems which may require you to completely reinstall your Windows operating system. Our advice is NOT to attempt stop an already scheduled chkdsk operation.

Even Microsoft warns that if you use Registry Editor, you do so at your own risk! More information about stopping or canceling a scheduled chkdsk operation is available directly from Microsoft.