How to format a windows 7 computer.

You can't really factory reset a computer. You could try Windows System Restore. If you have Windows 7, then your computer has probably been make "restore points" that will let you go back to the state of the system on that date. Maybe there's a restore point close to your purchase date....

Want to go thermonuclear?

1. Back up all your files. I'd make 2 backups.
2. Make sure you have all the CDs that Dell sent you with Windows and drivers. If you didn't get those disks with your computer, call Dell and tell them you need them; they should ship them for free. (It seems like Dell decided a couple of years ago that almost no one was using those disks, so they stopped sending them out with new computers.)

OK, here comes the thermonuclear part. You are about to erase *everything* on your hard disk: Windows gone, programs gone, files gone. You will have to reinstall Windows and your programs, and restore your files from backup.

These instructions are for Windows 7, but should be close for other versions.

To install Windows 7 using the Custom option and formatting the hard disk

To format your hard disk during Windows 7 installation, you'll need to start, or boot, your computer using the Windows 7 installation disc or USB flash drive.

1. Turn on your computer so that Windows starts normally, insert the Windows 7 installation disc or USB flash drive, and then shut down your computer.
2. Restart your computer.
3. Press any key when prompted, and then follow the instructions that appear.
4. On the Install Windows page, enter your language and other preferences, and then click Next. If the Install Windows page doesn't appear, and you're not asked to press any key, you might need to change some system settings. To learn how to do this, see Start your computer from a Windows 7 installation disc or USB flash drive.
   
5. On the Please read the license terms page, if you accept the license terms, click I accept the license terms, and then click Next.
6. On the Which type of installation do you want? page, click Custom.
7. On the Where do you want to install Windows? page, click Drive options (advanced).
8. Click the partition that you want to change, click the formatting option you want to perform, and then follow the instructions.
9. When you've finished formatting, click Next.
10. Follow the instructions to finish installing Windows 7, which include naming your computer and setting up an initial user account.

Now you have a spanking clean computer.

How to Format a Computer with Windows 7 Warning - Formatting hard drive information does not permanently erase the data. Even after a computer has been formatted, deleted files can be easily recovered. If you want to permanently wipe your hard drive by completely overwritting hard drive data, check out various programs that will ZERO out the drive.
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To format your hard disk during Windows 7 installation, you'll need to start, or boot, your computer using the Windows 7 installation disc or USB flash drive.

1. Turn on your computer so that Windows starts normally, insert the Windows 7 installation disc or USB flash drive, and then shut down your computer.
2. Restart your computer.
3. Press any key when prompted, and then follow the instructions that appear.
4. On the Install Windows page, enter your language and other preferences, and then click Next.
5. If the Install Windows page doesn't appear, and you're not asked to press any key, you might need to change some system settings. To learn how to do this, see Start your computer from a Windows 7 installation disc or USB flash drive.

On the Please read the license terms page, if you accept the license terms, click I accept the license terms, and then click Next.
On the Which type of installation do you want? page, click Custom.
On the Where do you want to install Windows? page, click Drive options (advanced).
Click the partition that you want to format and click Format.
If you have more than one partition on this hard drive and want to get rid them to make one big drive again, then select a partition and click on the Delete option for each partition. Once you have deleted all of the partitions, select the Unallocated Space partition and click Format.
Pick the formatting option that you want.
When you've finished formatting, click Next.
Follow the instructions to finish installing Windows 7, which include naming your computer and setting up an initial user account.
If you do not want to reinstall Windows 7, you can cancel the installation at this point and keep your newly formatted drives.

This information has provided by, youc an also find instructions for other operating systems here: How to Format Computer

proceed according. God bless you

1. Create a New Partition
   • 1 Launch the Disk Management tool on your computer running Windows 7 by opening the Start menu and typing "diskmgmt.msc" in the search bar. The Disk Management tool, showing all connected storage devices, appears.
     
   • 2 Pick the hard drive onto which you'll install Windows 8. The normal choice is Disk0, which is the primary hard drive. This disk should already show your C: drive, and possibly other items like recovery partitions.
     
   • 3 Verify the available free space on the selected disk. For most computers with no other dual-boot setups installed, the entire drive should be occupied, so you'll have to shrink an existing drive (like C:). If there is a section with a black bar titled "unallocated," then this represents free space not currently in use.
     
   • 4 Shrink your C: drive by right-clicking on it and selecting "Shrink Volume." The computer assesses and reports how much free space is available on the disk. You need a minimum of 16GB of free space to install 32-bit Windows 8 and 20GB of space for 64-bit Windows 8. Type either 160000 or 200000 in the "Enter the amount of space to shrink in MB" box. Increase that number if you want additional storage space for files and programs within Windows 8. Click "Shrink" to continue.
     
   • 5 Right-click on the new unallocated space and select "New Simple Volume." Leave the defaults, ensuring that NTFS is selected as the file system type. Give the drive a name, like "Windows 8."
     
   • 6 Insert your Windows 8 installation disc or USB drive into your computer. When the new drive is formatted, restart the computer and boot from your installation disc or drive.
     
   Install Windows 8
   • 7 Select "Custom" during the Windows 8 Setup initialization process.
     
   • 8 Select the new drive you created when the installation program asks you where you want to install Windows 8. Be sure to select the drive with the label you used for the new drive; if you install to the C: drive, you will overwrite your existing Windows 7 installation.
     
   • 9 Follow onscreen instructions to install Windows 8.
     
   • 10 Reboot after you install Windows 8, ensuring that you've removed any installation media. When the computer restarts, you are presented with a boot screen that lets you pick between Windows 7 and Windows 8.
     

This will walk through the steps to create a bootable USB flash drive for the purpose of installing a Vista or Windows 7 OS. These instructions assume that you have a computer with Windows Vista installed on it.
Required:
· USB Flash Drive (4GB+)
· Microsoft OS Disk (Vista / Windows 7)
· A computer running Vista / Windows 7
Step 1: Format the Drive
The steps here are to use the command line to format the disk properly using the diskpart utility. [Be warned: this will erase everything on your drive. Be careful.]
Plug in your USB Flash Drive
Open a command prompt as administrator (Right click on Start > All Programs > Accessories > Command Prompt and select “Run as administrator”
Find the drive number of your USB Drive by typing the following into the Command Prompt window:
diskpart
list disk
The number of your USB drive will listed. You’ll need this for the next step. I’ll assume that the USB flash drive is disk 1.
Format the drive by typing the next instructions into the same window. Replace the number “1” with the number of your disk below.
select disk 1
clean
create partition primary
select partition 1
active
format fs=NTFS
assign
exit
When that is done you’ll have a formatted USB flash drive ready to be made bootable.
Step 2: Make the Drive Bootable
Next we’ll use the bootsect utility that comes on the Vista or Windows 7 disk to make the flash drive bootable. In the same command window that you were using in Step 1:
Insert your Windows Vista / 7 DVD into your drive.
Change directory to the DVD’s boot directory where bootsect lives:
d:
cd d:\boot
Use bootsect to set the USB as a bootable NTFS drive prepared for a Vista/7 image. I’m assuming that your USB flash drive has been labeled disk G:\ by the computer:
bootsect /nt60 g:
You can now close the command prompt window, we’re done here.
Step 3: Copy the installation DVD to the USB drive
The easiest way is to use Windows explorer to copy all of the files on your DVD on to the formatted flash drive. After you’ve copied all of the files the disk you are ready to go.
Step 4: Set your BIOS to boot from USB
This is where you’re on your own since every computer is different. Most BIOS’s allow you to hit a key at boot and select a boot option.
I used these instructions to get my new Dell Mini 9 laptop loaded with Windows 7 (the PDC bits). HTH.