iPhone remain black and unresponsive for long period

[Linoo]

Hello,
I am new to this forum. I have iphone 3gs which is 3 months old. It has amazing features and it looks very descent. It works very well until last week. From last week my iphone repeatedly goes black and unresponsive for long time period. In such time none of the button works and then after some times it works as usual. I don't know why this happened. Can any one tell me how to fix this problem.
Thank you.

[Bon-Z]

It seems that for long time you haven't reset your iphone. In iphone due to lots of feature it filled with lot of unwanted stuff like cookies, cache, saved file, etc. These unwanted stuff some times affect your iphone. So in this case you have to reset your iphone. You can reset your iphone in following ways.
1.Go to setting option -> now go to general setting -> select Reset option-> now click on Phone Reset -> wait for few minutes -> now your iphone will be come to it's original form.

2.You can hard reset your iphone by pressing sleep/wake button and home button simultaneously until logo of apple appears.

[Gonzo]

I also had the same problem then one of my friend said me how to fix this problem. after using his tricks now my iphone works very well now. Next time when your iphone goes to black and unresponsive mode just try following steps.
Hold the power turn on/off button and the Menu button simultaneously until logo of apple appears, it will restart your iphone to normal position.
I think this will help you.

[Pugsly]

Try to reset and restart your iphone. If that also not works then you have to restore your iphone with new version of operating system. You can restore your iphone in following ways.
First connect your iphone -> format your iphone normally -> open iTunes application -> in the right-hand side you can see Restore button -> just click on it -> let the Restore process complete(Restore process install new version of Operating System in your iphone).
After this if you still have the same problem then there is some serious problem happened to your iphone, in this case you have to contact your nearest apple store.