Occasionally gods have died due to lack of followers, but if they’re part of a pantheon can the other deities go “Hey, my followers, worship this guy until he can get back on his feet”? 1)
Okay, first thing: ALL of the answers I’ll be giving you are for the Realms and its deities and cosmology only.
Yes, other deities can issue instructions to their mortal worshippers, through dream-visions and manifestations…#Realmslore

— Ed Greenwood (@TheEdVerse) May 27, 2020

2)
…(e.g. speaking out of altars or temple brazier fires), and via clergy. However, mortals have free will; they may or may not obey; it’s up to them.
And your question is rooted in monotheism; it’s important to remember that 3)
…all sentient, sane beings in the Realms “believe in” and worship ALL the gods, not one god. It’s extremely rare for a deity to die from lack of followers. Cease to be a deity, yes, but it’s usually other things that kill…#Realmslore

— Ed Greenwood (@TheEdVerse) May 27, 2020

4)
…them (other gods, for example).#Realmslore

— Ed Greenwood (@TheEdVerse) May 27, 2020

Hey @TheEdVerse , if you had to pick your top 5 publications that had an abundance of knowledge/lore useful to newer DMs(trying to catch up) running games in the Forgotten Realms, what would those be? There's so much content sometimes its hard to know where to start.

— Michael Butler (@thembutler) June 6, 2020

1)
I get asked this a lot, and the answer depends on where (geographically) you are setting your games, and their nature (urban, wilderness, underground). The Sword Coast Adventurers Guide is your 5e baseline, but for more depth and wider geographical coverage, I’d 2)
…add the 3e core book, the Forgotten Realms Campaign Setting hardcover; it's the largest and most comprehensive overview Realms fact-guide published. To it, I'd add EdGreenwoodPresentsElminster'sForgottenRealms for details of life in the Realms, and then the…#Realmslore

— Ed Greenwood (@TheEdVerse) June 6, 2020

3)
…2e Forgotten Realms Adventures hardback for a broad city overview.
Then decide where you want to adventure: the various 5e super-adventures provide the best up-to-date coverage of places (for example, Storm King’s Thunder covers the 5e Sword Coast North), and 4)
…if I did a 2e Volo's Guide to an area you want to use, grab it! Then decide the nature of interests: 2e Cloak & Dagger if you want shadowy organizations and intrigue, 3e Lost Empires of Faerun if you want old ruins to explore, and so on.
Then go to the FR wiki to look up…

— Ed Greenwood (@TheEdVerse) June 6, 2020

5)
…specific things. All entries have their published sources at the bottom (the footnote citations lead there) and that will show you which specific books, adventures, and magazine articles covered the elements you want. Anything not covered? Ask me!#Realmslore

— Ed Greenwood (@TheEdVerse) June 6, 2020

@Dan_Dillon_1 @JeremyECrawford if i cast armor of agathys on myself and then someone polymorphs me or i polymorph myself, do i still have the armor in the new form?

(like if someone hits me as a giant ape, will they still take the cold damage?)

— ℙ ℝ ℂ ℍ (@Tris10_outta_10) May 17, 2020

Armor of Agathys (PH 215) and Polymorph (PH 266) do not make exceptions to each other. Since temporary hit points are separate from your actual hit points (PH 198), they would not be replaced by the statistics of the new form. Yep, existing spells on you when you polymorph are still there in your new form.

— Dan Dillon (@Dan_Dillon_1) May 17, 2020

Confirmed.

— Dan Dillon (@Dan_Dillon_1) August 21, 2020

Situation: wizard has clone in reserve. Wizard casts Wish, suffers stress, loses ability to cast Wish, dies and soul enters clone. Does the stress follow into the clone?. Does the loss of Wish persist? (Different via Reincarnation?) That wizard's ability to cast wish is gone forever. Incarnations, bodies, resurrections, clones, none of that matters. No wish casting ever again.

— Dan Dillon (@Dan_Dillon_1) August 14, 2020

It goes with my personal take on the RAW, too. (Unfortunately, for two of the groups, DD responding doesn’t make for RAI SA clarification — only JC counts per the groups’ rules. But it works for two other, larger groups (several thousand members) so that helps, at least. 😉 )Dan's response is correct.

— Jeremy Crawford (@JeremyECrawford) August 14, 2020