For got the phone password - Samsung SGH-t819 Cellular Phone

Check out this link below to download a PDF manual, software, and more for your phone. Just copy and paste into your browser.

http://www.samsung.com/us/consumer/mobile/mobile-phones/t-mobile-phones/SGH-T819CNATMB/index.idx?pagetype=prd_detail&tab=support

Change Phone Password from page 150 in your manual:
The Change phone password feature allows you to change your current phone password to a new one. You must enter the current password before you can specify a new one. Once you enter a new password, you are asked to confirm it by entering it again.

You can try this:
How Do I Reset My SGH-T819?
To Reset the handset, to the factory default Settings, follow the steps below:

1. While in standby mode, press the left soft key for Menu
2. Select Settings (9)
3. Select Reset Settings (#)
4. Press the OK button to check the box(es) for the following:
• All: Phone, Display, Sound and Alarm settings will be reset to the default values
• Phone settings: Only the Phone settings will be reset to the default values
• Display settings: Only the Display settings will be reset to the default values
• Sound Profiles: Only the Sound Profiles will be reset to the default values
• Alarm: Only Alarm settings will be reset to the default values
5. Press the left soft key for OK
6. Enter the password, using the keypad, default password is “00000000”
7. Press the left soft key for Confirm
8. Press the left soft key for Yes to reset the handset