What's happened to my iPhone 4?

So I was on the phone to my mum and I had my headphones in so I locked it.
She hung up first and as she hung up I went to unlock my phone so that I could hang up (at the same time)
It went straight to my home screen and the whole thing froze…
I was trying to press some icons but it wasn't working at all… So, I thought, I'll lock it and then see if when I unlock it, it will be okay.
No. It now is just a black screen… It won't unlock, I've tried holding down the on/off/lock button, doesn't work. I've tried holding down the home button… Doesn't work.
I know that it is switched on because it vibrates when I put the charger in it, and it also makes the noise when I put it on loud.
It's not even like I can take the battery out and reboot it. There's nothing I can do.
I've tried taking the sim out and putting it back in.
It's just a dark screen…
Has this happened to anyone else?
What could of happened? And what can I do?

I've seen this before. It should resolve itsef

If this happened recently, then it may recover. But, this sometimes is not the case. If I were you, I would try to visit and Apple store if there's one near you and have them diagnose the problem. If not, you can try contacting Apple. It's better to have a fixed phone than not too. If you post this question here https://discussions.apple.com/...index.jspa the people (users or staff) may be able to help you.

Since the case does not seem to be the internal hardware itself, I think the LCD is the main problem. You can buy LCDs for 5-40 dollars. Try to get one with a digitilizer. There are many youtube videos showing how to replace the LCD. Another alternative is bringing it into an Apple Store or 3rd party store to get it replaced.

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