While I have not had a problem since 8 months with my iPhone 3G, on again tonight (I had off this morning for professional reasons, as I often do) it. when i tried increasing the iphone volume it resulted in to the screen lock that is my screen got locked automatically. Other times when i tried pushing the sleep buttons it would rather bring up the shutdown screen. Altogether it seems quiet shocking to me since it had been only 8 months after i purchased the iPhone.Please tell me how can i get rid of these iPhone 3G Screen lock/Volume key/Sleep button issues. 

Re: iPhone 3G Screen lock/Volume key/Sleep button issues
I would suggest you to restart the phone inorder to get rid of this issue so follow the instructions mentioned below:
Press the button on / standby until the iPhone displays the Shut Down option> drag the button Turn right to turn off the iPhone.
Press and hold the Home button and power on / standby until the iPhone restarts (do not know Turn off the option when it is displayed but you continue to hold the two buttons until the image of the apple appears.

Re: iPhone 3G Screen lock/Volume key/Sleep button issues
Good evening, I had the same problem today after turning off the iPhone. I would have to restore it on iTunes by getting the backup this afternoon but the iPhone does not mount on the desktop of my MacBook and it does not appear in iTunes, So if possible please try to give another solution since this solution does not resolve the issue. 

Re: iPhone 3G Screen lock/Volume key/Sleep button issues
It appears as your phone is messed up with a number of problems. That’s why you will have to go for the restoration of your iPhone. If your Iphone does not start working normally still then i would suggest you to contact the nearest apple store since your apple iPhone is still in the warranty period. Your problem will be solved for sure. 

Re: iPhone 3G Screen lock/Volume key/Sleep button issues
Such problems probably occurs when some of your phones part become damaged or loose. And it would not be good if you try to get this fixed on your own since it will void the warranty. you can simply try to get the best service only if this problem is solved by the apple store. Rush to the nearest. 

Re: iPhone 3G Screen lock/Volume key/Sleep button issues
Unfortuately if you can not connect pC and be recognized by iTunes it’s hard but you can jailbreak the possibly of a different way, and directly from your iPhone. Because unless and until you don’t jailbreak your iphone you will never get the application installed on your system and you cannot solve the problem.