A short break. When I have writer's block, I try not to push myself. Because the more I push the worse it gets. Usually I first go for a short smoke break (strongly not recommended for non-smokers!!), make myself a cup of tea or coffee and watch some YouTube videos, to completely distract myself from whatever is in my head which doesn't allow me to write. Then after a while maybe slowly start switching the mood of the videos towards the topic I am supposed to work on and set the mood up! This whole process would take around 15 to 20 minutes but it’s really effective.
Play around on variations of the song. Sometimes when I need to write a specific topic or mood, I play around it. For example, if I am supposed to write something slow and sad, and I have a rough idea of what I want to do with the melody, but I am not sure how to continue it from there, I would sit by my instrument (in my case it’s piano) and play around with the melody but in opposite mood. In a happy way with very moving and happy chords! Improvise on it. This way I am still playing with my main melody and main chords but just that slight change in the mood of the melody, would again, distract me from whatever is stopping me from finishing the song.
Starting the beat! Well, most of the time the drums beat can be the way it wants to be, and it is not 100% depended to the melody or mood or chords of the song. Therefore, sometimes when I am short and really have to start the project as soon as possible and don’t have the luxury of time to do any of the 2 option above, I start with the beat. First lay down the beat structure, which later can make minor adjustments on it and finalise it based on the finalized version of the song itself. This way, again, I am distracting myself and clearing my mind by focusing on something almost brainless as programming the drums! It has both distraction and time saving factors in it.
As by now you can see my main focus of breaking the “writers’ block” is to distract ourselves from whatever is creating that block. When we can’t just write, it’s most probably because there is something in our conscious or subconsciousness that is stopping us from thinking straight. All we need to do is to find that factor and solve it in ourselves and open the gate or if we can’t find what it is, just somehow trick our brain to don’t get itself much involved with it and make it to just move on to the next task it has to do, to write!