What usually helps me to get out of a funk is I have a particular playlist of songs that are "vibes" for either a specific character or even a specific rp/setting if there's not enough to separate the characters individually. So I just have that on in the background and see if it kick-starts anything. 

Going back and re-reading some of your old posts for that thread/character can also help too, maybe it's been a while since you wrote them and your brain is abit stuck because its forgotten what their "inner voice" sounds like, for instance. So re-reading old posts can help with that :) 

If you're genuinely just tired/burnt out tho, definitely don't try and [i]force[/i] force it to the point where you start to hate the hobby tho, that's the opposite of helping. You could try doing some other stuff for abit like watching a comfort show or movie, or if you're into that doing another art and craft project like colouring or sewing or something! Hope you've managed to get some good tips here and it helps ya out somehow! <3