Restore iphone 3gs without itunes?

I have researched this on Google and it seems the question i'm asking is related to phone theft but i can assure you i'm just an airhead not a thief.
Ok, so i lost my charger and my phone as been off for a week while my new charger was on order, in that time i have forgotten my password (not helped by the fact i change it so much to keep my daughter out of my phone). I messed up my laptop a few months back so i just downloaded itunes again to restore back to factory settings however i keep getting an error message and itunes won't allow the restore.
Can anyone tell me if its possible to restore my phone without itunes and of course without entering the phone itself? Also after restoring will i have access to my text messages as i have a few important texts that i'm currently unable to read.

Any help would be appreciated, thanks xx

Instructions
1
Back up the iPhone in iTunes before proceeding.

2
Find the "Settings" icon on your iPhone screen. The icon contains an image of gears. Tap the "Settings" icon.

3
Tap the line that says "General." It also has the gear icon.

4
Scroll down the screen until you see a line that says "Reset." Tap "Reset."

5
View the options on the screen, which include resets for settings, home screen, keyboard dictionary, network settings and location warning. To erase all data, select the line that says "Erase All Content and Settings." When you select it, a box pops up with a red button that says "Erase iPhone." Touch the red button and your iPhone erases all data on the phone.

The other way is this

If iPhone 3G won't turn on, or if the display freezes or doesn't respond
Press and hold the Home button below the screen for at least six seconds, until the application you were using quits.
If that doesn't work, turn iPhone 3G off and turn it on again. Press and hold the Sleep/ Wake button on top of iPhone for a few seconds until a red slider appears, and then drag the slider. Then press and hold the Sleep/Wake button until the Apple logo appears.
If that doesn't work, reset iPhone 3G. Press and hold both the Sleep/Wake button and the Home button for at least ten seconds, until the Apple logo appears.