How to keep 12 year old granddaughter occupied and happy

You say she is not near any of her school friends, but is there any possibility of inviting one to stay for a few days? Of course friend and her parents would have to be willing.

I was an only child but my mother usually arranged for a friend to come with us if we were going on holidays - even going to grandparents for a few days or a Sunday lunch. It must be very lonely for a 12 year old to be on her own with grandparents, no matter how hard you try to find activities for her.

Look in the local library and sports complex; they will have activities available and might spark suggestions for things for her to try, one day tasters.
See what subjects interest her at school (if any) and investigate if there are any online activities that would engage.
She seems to be going through a bad patch , and perhaps a period of boredom and also no pressure, however kindly intentioned, is what she needs.

Thanks ladies. She says she is not interested in joining anything. I might try again though, you never know. I might take her with me to a craft shop tomorrow and just see if she fancies trying something.

I don't take her with me when I visit my mother. Mum is quite unwell so I don't think its appropriate for either of them.

I think the comment about forcing her to be happy is a good point actually. I didn't think about it that way. I suppose I just want to 'fix' things for her and maybe it's just not possible.

I guess it depends where you live. Round our way there’s loads of activities for that age group in the holidays organised by different clubs etc. Youth drama, tennis, football, water sports, creative writing, music and dance.

It might be a bit late to sign up for some, but worth looking?

I don't think you can force her to be happy, I'm afraid. She maybe just needs to be on her own at times. After all, she's nearly a teenager. Ask her what she would like to do? Although that risks a shrug, and "nothing." Take her shopping to buy something for her? Teach her to knit, sew, crochet. I know you said she isn't into crafts, but maybe she doesn't know how. Does she have to go with you when you visit your mum? If so, that could be very boring for someone her age. Ask her what her favourite authors are and encourage her to read. Teach her card games, play board games. Do a jigsaw together against the clock. I think she needs space though