While deleting photos the screen froze and then went black.

My phone has little memory and being of the older generation( meand the phone) I delete what I do not need and I assume this helps with the memeory available on the phone. I was deleting photos - one at a time - when the screen froze and then when I hit the back button it went black. And now there is nothing - won't turn on or respond. Plugged in the charger but also no response. I had noticed that the background on the homepage seemed darker but thought I probably had accidentally changed brightness settings or something - not a committed phone user. Phone is well looked after - not used continuously, never near water and never dropped and no cracks on the screen.

Thankyou.