images – something weird happened

Something very strange has happened. My images uses to link properly and now they are all messed up.

The default for an image used to be like this https://www.mysite.com/post url

Now I have noticed that some are like this
https://www.mysite.com/attachment_id=222

some are not linked

and a bunch are like this

https://www.mysite.com/wp-content/up0loadpath/postURL

I had changed my theme and regenerated thumbnails. It is a huge amount of work to go back and fix everything one by one – does anyone have any suggestions as to what I can do?

Thanks,