It is possible to reformat a netbook with a flash drive if you use the program unetbootin. Unetbootin requires you to have a working operating system and an .iso file (a disk image of the new operating system you will be replacing the old one with. If ran from your desktop computer, unetbootin will give you the option to download a disk image, in this case, linux disk images. Linux is an open source operating system available for free. Or if you prefer to have Windows on your netbook, you will need to find the original Windows disk that came with your netbook, if any, or buy a Windows disk, and extract the .iso from the disk using .iso extraction software on a desktop computer with a disk drive. If you don't have a desktop computer or don't know anyone with one who would let you borrow it to extract the Windows .iso, visit your local library and request to use their computer for that. Extracting an .iso file is time consuming. Alternate: acquire a Windows disk image from the Internet by download. It is up to you how you accomplish that. You must then complete the form on unetbootin to prepare the disk image on your thumb drive. This is as easy as locating the disk image you wish to write to the thumb drive on your computer, then clicking next. When the procedure is complete, restart your computer with the thumb drive plugged in a USB port in your computer. When the computer boots, you should see a prompt on the screen to "press the * key to enter BIOS setup" or "press the * key to change boot options". Popular keys that manufacturers use are or . Look through your BIOS options, which are unique, and move the thumb drive up in "boot order" so your netbook boots from the thumb drive. After the BIOS option is set, reboot your computer once more, and if you are successful, your prepared thumb drive will boot whatever disk image you put on your thumb drive. Follow the disk's instructions to reformat your netbook.

To put it simply, step by step:

1. Acquire a flash drive (recommended 2gb+ for Windows XP, Linux, 4gb+ Windows Vista, windows 7).
2. Use a working PC to download a USB boot preparation software such as unetbootin to prepare an operating system disk image to be written to the thumb drive.
3. Write the disk image to the thumb drive using the unetbootin software. It will prepare the USB drive for boot, which may take at least 10-30 minutes.
   1. System BIOS is unique to the computer, the process will vary, but the phrase you want to locate is "boot order"
4. Change your system BIOS options to boot from the thumb drive first.
5. Restart your computer and follow the instructions from your disk image

If all goes well, you have reformatted and reinstalled an operating system on your netbook without the use of a CD drive (assuming you didn't need to extract the disk image with disk image extraction software). Brute force approach is to buy a USB disk drive and install a disk that way, but the way I described will get it done for free, assuming you have a recovery disk. Good luck!