How do I get over this block?

Lily Don't give up now. You can't learn as quickly as young people but your brain is still working and when you start again you will see(hear) progress.
If new chords put you off then practice the old chords find an old fashioned guitar book and bang off some chords one after another.
I am relearning the piano using an e-piano and I play scales when I am too tired to think. I am now after two years, further than I ever was but I can't play anything by heart which is what my GDs do.
GO and get your guitar and sit down and play for 5 minutes and the next day for 7 minutes..............

Thanks very much for your encouragement. I shall try all your suggestions, I do like wildswan's idea, the girls will love to hep and perhaps I can show them how not to give up at the first hurdle.

Do you think if I got the red wine out I could copy the Rolling Stones ideas and come out playing 'Do You Think I'm Sexy? (I doubt the grand daughters would never speak to me again if I did that.)

This is an opportunity for your grandchildren to step up and "help" granny. It's good for children to know that grown-ups can't do everything. So let them know you are struggling, ask them to show you again, play simple tunes with you etc etc. They will love to have a bit of role reversal for a change and you will strengthen your bonds with them. While helping you they will also improve their own skills.

Laugh at yourself for being silly and not as good as them. Use it as a way to do something together and don't worry too much about your proficiency.

Try doing what the Rolling Stones do when they are going on another tour without having played for a while
Go in the room and look at the equipment
Go back the next day and touch it
Go back the next day and pick it up
Go back the next day and strum a chord
(I think there was alcohol involved somewhere but not sure when that fitted in!)?
Be a shame to give up now. I am a bit the same with my quilting when I have finished a project and put all the stuff away. I think you just have to try playing a bit and see how you get on. Good luck.

You have to get over this feeling. It’s hard when you start any instrument as you can only play silly little songs I know.

But, Christmas is coming. Get out to the nearest Music Shop. Browse and find some simple Christmas Carols and songs. While you’re there buy a cheap tambourine, or some shaker bells. Then get your GDs together and arrange to put on your own little Carol Concert playing, singing and a bit of percussion.

Go for it! ?