Why is my screen frozen and how do I fix it?

I pressed an image in social media to download it. A 'thumbnail' of the image appeared in the centre of the screen and stayed there.

At the same time, the touchscreen stopped responding. None of the icons (including the 'phone icon) work and I am unable to switch off the phone or reboot it.

I can't make calls and don't know whether I can answer them when received.

PLEASE HELP!!!!

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It's okay - PANIC OVER!

I looked up how to 'hard restart' the phone. When it rebooted the image was gone and the screen works again.

If anybody knows why it happened in the first place, I would be interested in hearing it so that I don't do it again.

Thanks for your time. Sorry if I wasted it.

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