You will have to call your provider and prove that you own the phone and the account and they will reset it
SOURCE: Unlock code
To accomplish the unlocking of your Samsung R210 Spex due to forgotten or unknown user lock code I used the following method. First, you will need a data cable. I bought this one from eBay...
Data cable
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&ssPageName=STRK:MEWNX:IT&item=260427509638
Create a folder on your desktop. I named mine Samsung R210.
When you plug your phone into the PC it may be recognized and work. If not you may need the USB drivers also.
Unplug the phone.
Open the Samsung R210 folder and create another folder. I called mine USB driver. Download this driver to the USB driver folder...
http://forums.mobiledia.com/cgi-bin/redirect.cgi?http://members.chello.nl/dondiegox/Samsung/Flashers/Z100_Downloader.zip
In the zip file there's a folder called Samsung_USB_install
Unzip it into the USB driver folder also and click on setup.
Reconnect the phone.
Check the control panel under USB and ports COM and LPT. My phone appeared on COM 10 under ports COM and LPT.
Next, create two more folders inside the Samsung R210 folder. I called them PST and Cricket DLL. Download Samsung PST lite and DLL installer files from the following two links into their respective folders.
Samsung PST lite...
http://www.mobile-files.com/forum/attachment.php?attachmentid=2274&d=1105395154
Cricket DLL file for the PST...
http://www.megaupload.com/?d=N3XTCO3W
Unzip them both into their same folders.
Run the install for PST.
Run the install for the Cricket DLL.
There should now be a shortcut on your desktop named Samsung PST lite. Double click it and you should see the PST Lite window.
Double click SCH-R210 on the right.
This should show you the unlock code in the next window. 
If you don't see the info click the read general information button at the bottom. Write down the user lock code or be sure to remember it. Close the windows. Disconnect the phone. Enter the lock code into the phone and you should be free!
PS, I got my R210 Spex off eBay for $0.01 because it couldn't be unlocked! I have a feeling those prices will go up now that this info is on the web.
SOURCE: changed nam on phone that changed lock code,need unlock code
when phone turns on it probably says something in the way of needs initial set up or something simular? at that screen just hit clear button which will take you rt back to default screen then hit center menu button go to settings and then to phone settings,nam and chaNGE back to nam1,hit ok . phone will restart and come back on with everything normal again,let me know if different happens!
SOURCE: Sch u820 can't unlock
As you have not specified in particular what is the unlock code required for you, i am giving the ways to unlock all the codes
NETWORK UNLOCK CODE:
You can unlock it by flashing your mobile if your mobile is a CDMA mobile...
The procedure for flashing your mobile is in the link below
http://hubpages.com/hub/How-to-Flash-your-cell-phone
It has an video explanation.
If
your mobile is not an CDMA mobile , you can get the network unlock
code(NUC) by just contacting the current network provider customer care
department.It is free of cost.
The restriction code can be got
from your old service provider..This restriction code is kept to prevent
someone who stole the mobile from using it with another provider...
They will have a security check done with your date of birth etc..to verify whether you are the exact owner of the phone..
After that they will provide you the restriction code to unlock it and use it with another service provider..
It is all free of cost do not pay anyone for this seeing some advertisement over internet . That is all fake ads.
The above procedure works and you can verify that by seeing the rating of an happy customer here..
http://www.fixya.com/support/t4979448-need_unlock_motorola_razor_v3_from_optus
PUK CODE:
PUK code can be given only by your service provider which is specific for each and every mobile number.
Contact
your sim customer care department over phone. Its free of cost to get
the pin or puk no. If you cant contact through your phone get some other
phone and contact them.
Go to the nearest service outlet of your service provider they can also help you.
There is no other go than the above procedure only your service provider can give it nobody else in this world nor any software.
Go
to the below link and you can confirm that the above procedure works
and there is a testimonial given by the customer too.
http://www.fixya.com/support/t3079596-sking_puk_code
PIN CODE:
HI If you are asking for pin contact your service provider , he will give you a default pin .
If
you try pin more than few predefined no of times your phone will ask
PUK code which can also be given only by your service provider which is
specific for each and every mobile number . Do not try PUK(new pin code)
code many times or else your sim will be blocked and you will need a
new sim.
Contact your sim customer care department over phone. Its free of cost to get the pin or puk no.
Go to the nearest service outlet of your service provider they can also help you.
There is no other go than the above procedure only your service provider can give it nobody else in this world nor any software.
SECURITY CODE:
If
it is lost nothing can be done. You need to flash your mobile at an
authorized service center which will reset the mobile memory and also
all the data inside the mobile will be lost.
SOURCE: how do i unlock my samsung sch-u820 phone
how do i unlock my verizon samsung phone i 4got the pass word and the phone is lock
Steps to Restore Phone
This will return phone to the default settings and permanently erase all user data, including pictures,videos, music, messages, contacts and downloaded applications stored on the phone.
http://www.resetcellphone.com/how_to_reset_Samsung_sch-u820-reality
99 views
Usually answered in minutes!
×