Check system. Then press [F11] Key.

Just press F11 key once you power on the laptop. Should automatically take you the factory reset screen.

If not, that factory partition is erased or you didn't press the F11 at power up.

If your system does have a recovery partition (typically says press f11 for recovery during boot if you have one) Reboot the pc, press f11 during the asus screen. The system restore utility will guide you through the rest.

If your system does not have a recovery partition
Take your system restore or operating system disc, Put it in the cdrom, reboot the computer.

When your pc starts back up (during the asus logo screen) During this screen there is usually a key sequence you can press to pop up the alternate boot menu. Typically the key is esc, f8 or f10. If one of those is right it will bring up a second menu asking what to boot from, select your cdrom. The cd will boot and your system restore disc will guide you through the rest..

Have you try to press the F11 button ?
Turn off the computer,press the "Power" button. Wait for the eMachine's computer to reach the screen that reads "Press F11 to start recovery." Once this screen appears, press the F11 key on the keyboard multiple times to make sure that it registers. If the recovery screen does not come up, you will need to turn the computer off and back on again and attempt to press the F11 button again when the prompt appears.
After doing that is only necessary to follow the steps.

i suspect your f11 key does work, try opening a web browser and while it is open press the f11 key if your browser goes full screen the f11 key works just press f11 again to return it to normal. Try pressing and holding the fn key and then press f11 that will switch your wireless on and off

Hello, when starting up the computer hit 'F11' on your keyboard and it should bring you to a screen which will allow you to reset your computer back to it's factory settings with the original Operating System installed and all other software that originally came with the computer.
Please proceed with these steps with caution as all files will be erased.

If the DeLL Post screen comes up it means that your laptop is okay. Pretty much your windows is corrupted and that's the reason why it's not starting up.

Things that you can do: (for windows vista & windows 7 only)

1. Restart the PC and immediately press F8. (You need to tap/press F8 repeatedly while starting up). You should get a screen that says "Advanced option menu."
2. Select Last known good configuration. If it does not work. restart the pc and press F8 again.
3. Select Repair your computer.
4. Run start up repair. If nothing happens. Run system restore. If it fails, the boot manager file of windows is corrupted.

Last option, you could try Dell PC Restore by pressing CTRL + F11 at the same time while the system is starting up. (You could start pressing CTRL + F11 when the DELL flash screen comes up).

NOTE: Running Dell PC Restore will erase your files/data & put your system back to factory settings.

At start up go to the BIOS by selecting the proper F key. When in the BIOS mode look for instructions at the top or bottom of the screen to hit F keys like F10 for System Recovery.

you need to press the

ctrl + F11 as soon as you see the Dell logo screen when you turn on the computer.

the trick is. as soon as you turn on the computer, press and hold on the ctrl key then keep tapping the F11 key.

System recovery can be accessed during initial boot up before the Windows screen comes up. In most cases you need to press F11 to begin system recovery. There should be a message that flashes across the top of the screen shortly after you turn on the computer that instructs you to press F11 for emergency recovery. Do it. If you do not see a message, try pressing the F11 key several times right after you start your computer, sometimes the message to enter recovery does not appear because the manufacturer places there logo page on the initial screen.

If system does not start on your A21 you may need to reinstall the system. To perform a recovery or repair, do the following:

Make backup copies of your data files, if possible. Any files on drive C that are not backed up will be lost.
Do one of the following (for best results, use the F11 method):

If you are using the Product Recovery program for recovery purposes, turn off your computer for at least 5 seconds. Press and hold the F11 key while you restart the computer. When the Product Recovery program starts, release the F11 key.

Note: If pressing the F11 key does not start the Product Recovery program, then your recovery partition is corrupted, in this case you will need to use a Recovery Repair diskette.

If you are using the Product Recovery CD for recovery purposes, place the CD in the drive (if you have more than one Product Recovery CD, use Product Recovery CD 1). Then, restart the computer. The Product Recovery program starts.

Do one of the following:

If a menu is displayed giving you an opportunity to select an operating system, use the arrow keys to move to the appropriate operating system, press Enter, and then continue with the next step.

If an operating system menu is not displayed, continue with the next step.

From the Product Recovery program Main menu, make the appropriate selection (IBM Rapid Restore PC, Factory Contents, or System Utilities), and then press Enter.
Follow the instructions on the screen.

If your recovery partition is gone this company is offering a download of A21 restore disks for $19. You will need to download from them on a computer with cdrw, and then burn your recovery cd yourself.