Sorry to hear this.
Just to clarify, do you mean you no longer get alerts when someone likes a post? Looking back over your posts, it seems that both of you last posted in the thread last year sometime, so I'm hopeful that your latest posts could give the system a nudge and fix whatever was causing the problem.
Or did you mean email alerts when there's a new post? If so I'd recommend making sure you are still Watching the thread. This option is at the top right above each page of the thread (opposite the page numbers).
If you still have no joy, let us know in
the Help forum and we can look into it.