Brainstorm: Brainstorming helps you overcome writer's block by getting you writing about the fun parts of your work. The ideas, the characters, settings, and more.
Watch a show or movie in the genre. Chances are you will see something that will spark an idea for "I can do that" or "I can do something else better than that".
Phone a friend. If you have writer friends, belong to a group, or just need to bounce ideas off someone, call and talk to someone for a moment. Even if their suggestions won't work, they are still ideas and will help you get to what will work.
Write something else. Work on an unrelated project and see if it gets you back to where you were.
Ask questions: Why am I stuck? Is this story or writing piece going the way I want it to? Why not? Sometimes writer's block is an internal message that you should be writing something else and what you are working on now is not in alignment with your message.
Work out or do some form of exercise.
Paint, draw, build something; just about any other creative activity can clear your mind long enough for you to get back into it.
Move. Not everything, just you! Go to a different room or to the coffee shop.
Listen to music. Create a playlist for your current work in progress.
Don't beat yourself up if things are not going to plan. Create a new plan, a new character, a new story if necessary. Writing is a process, not a product. There is no such thing as perfect. We can reword, rewrite, re-edit everything.