why does my iphone keep blacking out?

I recall the whole "press and hold home/power" thing; tried it, to no avail... nothing happened no matter how long I held, all it did was take screenshots. The problem does not seem to be related to any app (it's happened in downloaded apps such as Facebook, Words w Friends, as well as native apps such as Settings, Messages). Restarting the phone didn't seem to help, have tried that several times. Phone just keeps blacking out.

I had the same problem and I tried to restart my phone and it didn’t work. So instead I when to go erase all my data but before I did that I reset all my settings So before you erase everything try doing that go to general> Reset> Reset all settings

First try a Reset ( No Data will be Lost )

Press and hold the Sleep/Wake button and the Home button at the same time for at least Ten seconds... (But can take Longer)... until the Apple logo appears. Release the Buttons

If no joy... Try a Restore...

1: Connect the device to Your computer and open iTunes.

2: If the device appears in iTunes, select and click Restore on the Summary pane.

Restoring > http://support.apple.com/kb/HT1414

3: If the device doesn't appear in iTunes, try using the Steps in this article to force the device into Recovery Mode.

Make sure you have the Latest Version of iTunes (v11.1.5) Installed on your computer

iTunes free download from www.itunes.com/download

Note on Recovery Mode.

You may need to try this More than Once... Be sure to Follow ALL the Steps...

Once you have Recovered your Device...

Re-Sync your Content or Restore from the most Recent Backup...

Restore from Backup > http://support.apple.com/kb/ht1766

Note:

Also consider Deleting any Apps you have Purchased / Downloaded but you now never use...