Google deindexed a post and ranked something else

Hello so google just recently deindexed one of my posts and ranked something with the URL mysite.com/embed/deindexedposturl

That post has now due to no content visible lost all its rankings.

What to do? How to ask Google to index the right URL?

set noindex tag to the second post,
send both to GSC to get crawled again,
give it some time and it will be back as it was

you have to block the path for such URLs in robots.txt tho,
to avoid any future conflicts

Hi
You can redirect 301 the second url to the main one.
Or you can use canonical tags and define the main post's url in both pages(It's possible to define self url in canonical tag. Check it's documentation for properly use).
Then re-index those pages in Google Search Console.
Best of luck