photostream panic - expert help needed

Hello, I was just checking that my Photostream photos were all protected before Apple delete the app today.

I found my old computer and there is still a Photo Stream album in there. I randomly clicked on one of the photos and tried it in my iCloud - it isn't there. So I then tried to find it in the library on my computer (it says These photos were downloaded from Photostream) but it isn't there either, so now I am panicking! Apologies, I have mentioned this in a reply to another thread, but now think I need urgent help. If anyone knows an Apple tech good with older apps I would really like to contact them via FaceTime or something and pay for their expertise in checking I am not going to lose all these photos. Or can I pay for one off Applecare?

Many thanks