Cleaning your Hard Disk is a process with several parts, but the main components are eliminating unwanted files, scanning your hard drive for errors, and defragmenting your hard drive.
Luckily, all three functions are built into your computers OS. To access them, first left click the Start button in the low left corner of the screen. In the right hand column of the menu that pops up, left click the My Computer item. In the menu that will pop up, there will be a listing of your systems Hard Drives, Floppy Drive (If you have one), Optical Drives (CD, DVD etc).
The Hard Drive is what's important. Each sort of drive has a different Icon in front of it, and the Hard Drive is the one that's rectangular with nothing coming out of it. And if you hold your mouse over your main Hard Drive and click your Right Mouse button, you'll open a mini menu of a variety of options. Move your mouse to the bottom of the menu and left click the item Properties.
The properties window should open with the General Tab active, and on it, next to a pie chart showing how much of said drive is filled will be a button labeled Disk Cleanup. During a number of operations, temporary files will be created on the disk to do the job, and sometimes these files are not deleted afterwards like they should be. By eliminating these files, files in your Recycle Bin (Which is where files are stored after you delete them just in case you change your mind) and a few others, you can often greatly increase the amount of free space on your Hard Drive.
Once you've cleared up some extra space on your drive, the next step is to go back to the properties window, and click the tab at the top labeled Tools. This will switch the window to one with the items Error Checking and Defragmentation.
Hard Drives are designed to be resilient to damage, but there's so much miniaturization involved that flaws will slowly develop in the drive. The drive's redundancies and error catching mechanisms will automatically handle most errors, but just in case, it can greatly improve your drive's performance to periodically have your system check the drive for errors.
The system is simple. In the Tools tag of the Drive Property Pop up window, click the button labeled Check Now in the Error Checking section. This will open a window offering you options in error checking, and you should check the boxes next to both Automatically fix file system errors and Scan for and attempt recovery of bad sectors. Once you've done this, simply click the Start button at the bottom of the window.
This will cause an alert message to pop up explaining that the Disk Checking program needs exclusive access to certain windows files, and thus can only work while windows in rebooting. It will ask you if you want to schedule a Disk Check for the next time you reboot, click the Yes button.
Now consider timing. The Error checking process can take half an hour to complete, making it a good idea to do this when you're taking a break from working on your computer for a meal or something that will take you a good bit of time.
Once you're leaving your computer alone for the required amount of time, you can reboot to start your scheduled Disk Scan. Just click the Start button in the lower left corner of your screen, then on the right of the line just above the Start button in the window that opens, click Turn Off Computer. This will open a window with three option buttons.
Click the one labeled Restart. This will cause your computer to shutdown, then immediately start back up. And partway through the boot up process, your system will begin it's scheduled Disk Scan. As mentioned this can take some time, so take the opportunity to stretch your legs, or have diner, or something.
After this prep work is done, it's time to begin the big disk improvement procedure, Defragmenting your hard drive.
Hard drives are designed to be able to break up information and record it in scattered regions of your hard drive. This design aspect greatly accelerates the speed at which data can be stored to the disk. When the fragmentation grows past a certain point, it starts slowing the speed at which your hard drive can be read. This in turn will cause your entire system to slow down whenever it does any procedure requiring data to be read or written to the hard drive.
Defragmentation is the method for repositioning data into unfragmented groups on the hard drive, thus eliminating the slowing effect of excess fragmentation
Just like Error checking, Defragmentation can be accessed via the Drive Property windows Tools tab. There are however a few concerns to think on before performing the procedure however. First of all, Defragmentation takes hours to finish. During that time you should not do anything with the computer, because operations that read and write data to the hard drive will disrupt the process.
A second related concern is the fact that many programs installed on your system will keep active in the background, and can perform enough read/write operations to disrupt the whole defragmentation process. Not every system will have this problem, but it seems common in my experience.
It's possible to shut down extra processes by hitting the keys Ctrl, Alt, and Del simultaneously. This will open a window with tabs showing active programs, running processes, and various system function information. But you need to understand your computer quite well to know which processes to shut down, and there is a simpler way.
Your system is designed with the option to boot into a highly 'stripped down mode called Safe mode. It's purpose is to let you boot up with virtually nothing running but the most basic processes, to make it easier to fix a lot of problems that would otherwise be running at this point. To make your computer boot in safe mode, first initiate a reboot. Click Start, click Turn Off Computer in the menu this opens, and then click Reboot in the small window this opens. Your computer will take a few moments shutting everything down before turning off and turning back on.
When the reboot starts, the first thing you should see is a screen detailing what sort of graphics driver your system has. Then it should open into a graphics screen, with the graphic varying based on your systems motherboard. At this point start hitting the F8 key repeatedly. You can stop when the system brings up a black and white text showing several booting options, and usually a highlighted boot up normally item. Click the up arrow key on your computer to move the highlight to the Safe Mode entry, and press Enter. This will reboot you in safe mode.
Now, click Start in the lower left corner of the screen, click My Computer in the right hand menu that pops up, Right click your system drive's icon, and click properties in the mini-menu. Then click the Tools tab, and click the Defragment Now button. This will open the Disk Defragmentor, and to start it, just click the Defragment button.
Since Defragmentation can take hours to finish, it's usually a good idea to do this as the last thing you do with your computer for the day, and let your system defragment overnight.