Q: hi can i change my password on my iphone from icloud ?

Hello erezedri,

It sounds like you need to remotedly lock your phone because it was stolen. If you had Find my iPhone turned on, you can do this with the following article named:

iCloud: Use Lost Mode

http://support.apple.com/kb/PH2700

1. Sign in to icloud.com/#find with your Apple ID (the one you use with iCloud).If you’re using another iCloud app, click the app’s name at the top of the iCloud.com window, then click Find My iPhone.
2. Click All Devices, then select the device you want to track or lock.
3. Click Lost Mode (iOS 6 or later), or Lock (iOS 5 or OS X v10.7.5 or later).
4. Follow the onscreen instructions, keeping the following in mind:
   • If your iOS device already has a passcode, that passcode is used to lock the device.
   • If you’re asked to enter a passcode, that passcode will be required to unlock the device.
   • If you’re asked to enter a phone number, enter a number where you can be reached. The number appears on the device’s locked screen.
   • If you’re asked to enter a message, you may want to indicate that the device is lost or how to contact you. The message appears on the device’s locked screen.

   Note:   If you forget the passcode, or if you set an EFI firmware password on your Mac before it was lost, then lock it and later find it, you may need to take it to an authorized repair center to unlock it.

 

• If your device is online, it locks and tracking begins (if applicable). If Location Services is turned off on the device, it’s temporarily turned on to track your device’s location. A confirmation email is sent to your Apple ID email address.
• If your device is offline, the passcode lock and tracking (if applicable) take effect the next time it’s online.

If you used Lost Mode, you see the device’s current location, as well as any changes in its location on the map.

Also please see this article for what to do about a stolen product:

What to do if your iOS device is lost or stolen

http://support.apple.com/kb/ht5668

Thank you for using Apple Support Communities.

Cheers,

Sterling