Artists block happens to everyone, no matter your craft. It usually happens at the most inopportune time when you are prepared, your schedule is free, you have a deadline and you are in the right mood. Learning how to stay motivated is a valuable skill that as is identifying what is causing the halt in your creativity. It is important to step away from your creative space and identify the block. It could be that your passion for that particular project has waned, in which case letting a fresh set of eyes and perspective may help re-ignite your ideas. Expectations or deadlines could cause stress or fear of failure and this will halt your flow of ideas.
It is important to creative every day whether it is a few lines written, a rough sketch or just jotting ideas down on a page. Step away when you need to, seek a second opinion when you can, keep a note pad or your phone handy when the inspiration comes and most importantly look after yourself, feed yourself, exercise, and be motivated by everything around you including other artists.