How to reset my iphone 4 with out the usb cord?

I need to reset my iphone back to factory settings. My password was changed and i don't have the usb cord. Is it possible?

To get to the reset part of your phone you must go to settings, rest. But since you forgot your password, I guess the only way is not by resetting but by restoring to factory default.
Maybe you could try iCloud.com enter your apple ID, and password, go to Find My iPhone, remotely set a lock or password. Go to your iPhone and type the password lock that you use remotely to lock your iPhone.
I had never try this, so I'm not sure if it works, but since you can't get in to your iPhone, is worth a try.

You'll want to use iPhone recovery mode when:

You've installed an iOS update and your device gets stuck in a continuous restart loop. This can happen when something goes wrong with the update, or when you have extremely low battery life when installing the update
You attempted to update the OS or restore the device from backup, the process didn't complete, and now iTunes doesn't register the device when you connect it to your computer
The silver Apple logo has been onscreen, with no change, for many minutes.

It's worth knowing that restoring your iPhone via recovery mode will delete all data on the device (if you go through the entire process; exiting recovery mode before completing a restore leaves your data intact), so it's best to sync the device to backup your data, if you can, before following these instructions.