iPhone back up failure

[onitlikeacarbonnet]

Anyone know why my phone stopped backing up 6 months ago?
And how I can fix it?

I had some storage issues so I'm paying for extra but I'm not using it as it won't back up.

I've tried turning my phone off and on and manually selecting back up but I just get a failed message.

I'm worried I'm going to lose my photos. Not bothered about anything else. I don't have music stored on iTunes or anything.

Thanks in anticipation

Mine backs up overnight, but it has to be plugged in to do it. I only know this because my iPad tells me it hasn't backed up for weeks because it hasn't been plugged in. Or something like that.

Yes, that's what's supposed to happen and it's plugged in overnight but the back up hasn't happened in months.
Was only today I thought of asking on here.
I'm not near an Apple Store, the shop I got my phone in has closed and the nearest one is too far to get there and back between drop offs and pick ups.
I'm sure it's something easily fixed but my tech skills are limited to switching on and off again and that hasn't worked.