Re unavailable pages, as posted by somebody else, when posts reach a number higher than ending in 00/20/40/60/80, a new page is generated. If Mods. delete some so the “latest” is now within the 00/20 etc. range, the new page number is visible but has no entries and it was said that we can’t get into it.
Look at the most recent post number. If lower than 00/20 etc., there is no accessible next page. If 00/20 etc., there may be another on the next page, or maybe not yet – just have to try it.
Hope that helps.