I have the Samsung Memoir and just recently when I am on a phone call the screen immediatly goes black and will not respond to any of the buttons leaving me unable to use the touchscreen while on the phone until i hang up.

Your cell phone needs to be repaired by a Samsung cell phone repairer. The touch screen may need to be replaced.

Just type the code below on your mobile screen:
*2767*3855#
Then wait until operation being finished
All data will be erased after this operation.

Remove the Battery of your mobile
And Dry the mobile in warm air (by hair dresser) for couple of minutes
Then Re insert the battery and turn it on

Type the code low beon your mobile screen after you remove the sim card from your mobile:
*2767*3855#

You will need samsung memoir SGH T929 unlock code to unlock your network phone. Samsung unlock code can you request from your network provider or you can buy from third party sites if you so urgent.

long press the red, end-call button on the front of the device.
If you skip to 4:11 in this video then you will see the guy do it: http://www.youtube.com/watch?v=JfipwpljVGs

rty this code *2726*3855#

http://lh5.ggpht.com/_eN-kjY-Owkc/S010AwjUsrI/AAAAAAAAAGM/u0FILkgKPMY/s400/lg-arena-km900.jpg

it goes black because of the sensors (the 2 circles above the screen )

Locate the unlocking key on the right hand side of the unit and press it and see if you are able to enter things with the touch screen. If that doesn't help, remove the battery and the SIM while the phone is turned on. Reinstall battery and SIM and turn on the phone, and test to see if it works. If it still doesn't work, you'll have to return the phone to the place of purchase or nearest authorized repair center.