Players won’t send me their character sheets?

I have 5 players in a campaign I’m hosting. We were supposed to meet last weekend, and had to postpone because 2 players all of a sudden could not attend. I have been asking them for over a month to create their character and send me certain details so that I can start planning the game’s story and session 1 accordingly. I have only received 2/5 players sheets, and my messages continue to get ignored. What should I do? Just plan a generic story based off of the two players who I have? Or not pet the other players play at all until I have their info in hand?

Edit: I posted a deadline for my players and they all responded! Game is on for Saturday for everyone. 🙂 I also wanted to clarify, I only asked them to pick their race & class, along with providing 3 fears, and to think about any god/patrons their character may worship/serve. That was all I asked of them.