I cant switch on my handphone. after i press on button... it only appear black screen

If the Sleep/Wake button doesn't respond, press and hold both the Sleep/Wake and Home buttons for about 10 seconds to force a restart.

Download the latest iTunes to your computer and reset the iPhone. Then re-sync it.
Reset

To reset iPhone, press and hold the Sleep/Wake button and the Home button at the same time for at least 10 seconds. During this time, a red "power off" slider may appear and the screen may go black, but do not release Sleep/Wake and Home buttons until the Apple logo appears.
If iPhone won't turn on, or the display freezes or doesn't respond

1. Press and hold the Home button for at least six seconds, until the application you were using quits.
2. If that doesn't work, turn iPhone off and turn it on again. Press and hold the Sleep/Wake button on top of iPhone for a few seconds until a red slider appears, and then slide the slider. Then press and hold the Sleep/Wake button until the Apple logo appears.
3. If that doesn't work, reset iPhone. Press and hold the Sleep/Wake button and the Home button at the same time for at least ten seconds, until the Apple logo appears

More resets:
Try This:
1. Remove Sim Card
2. Hold in 'Home' button and 'On/Off' button together until Apple logo appears
3. Replace Sim Card
4. Hold in 'Home' button and 'On/Off' button together until normal phone screen appears.


Also, Try this:
1.) Shut down the iPhone 3G.
2.) Start up iTunes
3.) Hold down HOME button on the iPhone 3G
4.) While keeping the HOME button depressed, plug in the Sync cable
5.) A message will pop up to ask if you want to reset.
6.) Just click YES and the reset process should start.

I’m happy to assist further over the phone at https://www.6ya.com/expert/joe_8b8c2cd6ce148309

try rsetting the iPhone:


Download the latest iTunes to your computer and reset the iPhone. Then re-sync it.
Reset

To reset iPhone, press and hold the Sleep/Wake button and the Home button at the same time for at least 10 seconds. During this time, a red "power off" slider may appear and the screen may go black, but do not release Sleep/Wake and Home buttons until the Apple logo appears.
If iPhone won't turn on, or the display freezes or doesn't respond

1. Press and hold the Home button for at least six seconds, until the application you were using quits.
2. If that doesn't work, turn iPhone off and turn it on again. Press and hold the Sleep/Wake button on top of iPhone for a few seconds until a red slider appears, and then slide the slider. Then press and hold the Sleep/Wake button until the Apple logo appears.
3. If that doesn't work, reset iPhone. Press and hold the Sleep/Wake button and the Home button at the same time for at least ten seconds, until the Apple logo appears

More resets:
Try This:
1. Remove Sim Card
2. Hold in 'Home' button and 'On/Off' button together until Apple logo appears
3. Replace Sim Card
4. Hold in 'Home' button and 'On/Off' button together until normal phone screen appears.


Also, Try this:
1.) Shut down the iPhone 3G.
2.) Start up iTunes
3.) Hold down HOME button on the iPhone 3G
4.) While keeping the HOME button depressed, plug in the Sync cable
5.) A message will pop up to ask if you want to reset.
6.) Just click YES and the reset process should start.

I’m happy to assist further over the phone at https://www.6ya.com/expert/joe_8b8c2cd6ce148309

I'd say your contrast is turned down, change contrast and brightness by pressing the buttons on your monitor.

Sorry for having read your post that late. I think you have already sorted it out by now. Anyway, in order to hard reset the 9502 by hardware means, press and hold both the blue Fn and the green phone buttons, and, at the same time, press the reset pin with the stylus pen. A white screen will come up asking for confirmation. Just confirm it (with the left softkey, if I'm not mistaken).

Hope it works for you.
Cheers!
Carlos

hi, this probably just means that you have too many applications open at once. If you press the middle 'hard' button, then press the triangle arrow tab at the top of the screen you should be able to see everything you have open and close everything at once. then your video shoudl work.

FORMAT YOUR HANDPHONE. TURN OFF YOU HANDPHONE, THEN PRESS CALL, 3, AND STAR THEN PRESS ON KEY. YOUR HANDPHONE WILL BE FULL FORMATTING.

Method:1
1. Switch off the phone.
2. Hold down the following three buttons: Green (call answer button, * button, and ‘3′ button.
3. While holding these buttons, press the power button and switch on the phone.
4. When the message ‘Formatting’ appears on the screen, release all of the buttons.
Method: 2 ( Hard Format)
1. Switch off the phone.
2. Hold down *#7370# button.
3. While holding these buttons, press the power button and switch on the phone.
4. When the message ‘Formatting’ appears on the screen, release all of the buttons.
Method: 3 Soft Reset
1. Switch off the phone.
2. Hold down *#7780# button.
3. While holding these buttons, press the power button and switch on the phone.
4. When the message ‘Formatting’ appears on the screen, release all of the buttons.

If iPhone won't turn on, or the display freezes or doesn't respond

1. Press and hold the Home button for at least six seconds, until the application you were using quits.
2. If that doesn't work, turn iPhone off and turn it on again. Press and hold the Sleep/Wake button on top of iPhone for a few seconds until a red slider appears, and then slide the slider. Then press and hold the Sleep/Wake button until the Apple logo appears.
3. If that doesn't work, reset iPhone. Press and hold the Sleep/Wake button and the Home button at the same time for at least ten seconds, until the Apple logo appears.

With switched on try pressing the camera casing around the edges of the screen. This may be a loose connector and squeezing the camera casing may rectify it - then may perhaps it will not. Try the menu button If it comes up look for the Reset function. Carefully look in the manual in case there is an error correction method. Failing all that Get onto the Samsung web site Technical Help.