Trying to force your brain to come up with ideas doesn`t work. It can apply to many situations where you “must” find an idea right now. Often you end up with no thought at all.
I have been there, feeling my ideas dried out. Struggling to think of something, anything. Exhausted of trying I gave up and took a break. I left home and went for a hike, about an hour in a flood of ideas almost overwhelmed me. I hadn’t expected anything leaving my notebook at home.
You don`t need to go for a long walk if you don`t want to, turn off your electronic devices, and sit in a quiet corner. It`s not easy always, but try to forget the ideas you need for a while.
Go for a visit, talk to a friend, or do anything other than thinking about work.
It`s often when I don`t need it I get the best ideas, so I try to remember to bring my notebook. When I come home I write down my notes in lists I have stored for later occasions when I struggle again.