Latvian List moved from NotABug to GitHub.
It's now in https://github.com/Latvian-List/adblock-latvian. The filter list URL is:
https://raw.githubusercontent.com/Latvian-List/adblock-latvian/master/lists/latvian-list.txt.
This was done because notabug.org periodically has various issues with network connectivity and not sending emails. It's also blocked by some corporate firewalls. Hopefully this move will also attract some people willing to help maintain the list.
Updating the list in all places it's referenced will take some time, since I don't really know all the places.
ABP people have been informed via email, for easylist.to there's https://github.com/easylist/easylist.github.io/pull/7. uBlock updated it (thanks to Dandelion Sprout creating the issue).