Ok, the MQ104 steps are 5, 10, 13 and 15. Now you can try (still stay outside of Dragonsreach when you do this) setstage MQ104 5 then go check if anything has changed. Check your journal. After setstage 5, it should say to talk to the Jarl. If nothing, try setstage MQ104 10 and it should put the note in your journal about finding the dragon stone. If nothing, try 13 which triggers "dragon has been sighted" and Irileth has asked for you to come to talk to the Jarl. And then 15 is the one to meet at the watchtower.
Do not do these all at once. You only want to go as far as it takes to get it going again but no further. Each time, step out of Dragonsreach and then back in. Those are the NPCs that should be changing and I don't know how well they update if you already have the area loaded. For the watchtower one, just make sure you're inside of Whiterun or Dragonsreach and not in the wilderness outside Whiterun.