I don't have ideas, I make them. But you need to practice that.

Get pen, paper, timer. Pick a topic to write on. Set timer for ten minutes. Start writing. Keep your hand moving. Don’t stop to reread the line you have just written. Don't cross anything out and don't worry about spelling or grammar. If you are stalling, come back to your topic. Don’t stop until the time is up. Keep your hand moving.

Good topics include "I want to write...", "I don't want to write...", "I remember..." and "I don't remember..." I use those regularly and find they often give me useful ideas. But after you are comfortable with this technique and have properly warmed up, you can push yourself further. Set the timer for fifteen minutes and write as many short idea snippets as you can in that time. Aim for at least thirty. Repeat immediately. The quality of ideas is irrelevant. Your first twenty will be boring and predictable anyway. After that, you usually start to loosen up.

This type of freewriting, called writing practice in Natalie Goldberg's Writing Down the Bones, will solve every and all problems in writing, if you learn to use and trust the method. Ten minutes of focused writing practice will always trump an hour of staring at the screen.