I've made a slight miscalculation

So I set aside the entire night to write some more 2G but I made one small mistake.
I have no idea what to write.
Normally I start writing with a plan [I have the BIG plan pretty much set, I'm talking about the 'this chapter' plan] and have thought about at least a major point or two from the chapter in some detail the days before.
Didn't do that...
My only thought I've given it is 'I will start writing again tonight' and I have no idea what to. So, I think the best thing to do is to cut my loses and do something else and put some shower/laying awake at night overthinking everything thought into it and try to set some time aside tomorrow or the day after.
Here's hoping.