Inspiration doesn't always appear when you want it to. When you're short of ideas there are several recommended ways to get your creativity flowing. You could try an exercise like describing the room you're in, or writing a letter to a friend (real or imaginary), or simply writing down the first things that pop into your head without attempting to edit them. These are all good, so take your pick.
One of my favourite ways to get my writing brain working is to write a review. There are benefits to this that you don't get with the other methods. First of these is that you have the pleasure of reading or watching something at least once in order to review it. Do this with your reader/viewer's head on i.e. for entertainment, so your initial reactions will be natural, and you won't be looking particularly for faults. Jot them down at the end, then read/watch the book/film/TV show/ whatever again with a few headings in mind, such as characters, plot, language, pace, or sets, costumes, acting etc.. This will help to highlight what worked, what didn't and why–all things that are helpful for your own writing.
Next, you need to structure your review, which will be determined in part by whether you are writing purely as an exercise or whether you intend getting the finished review published; a magazine is likely to want a different style from an online store such as Amazon or Smashwords. If you can come up with a great hook to start, and draw your thoughts to a conclusion at the end, so much the better. Be aware of potential spoilers, and if you can't avoid them, warn the reader/viewer about them.
The idea is to help readers/viewers decide whether they're likely to enjoy the piece. Don't be dishonest. Being non-committal is almost as bad. What point is there in the review without an opinion? You should avoid being brutal. Sarcasm may look clever, but it's unhelpful to the author/actors etc.. Ask yourself how you would feel if someone made those comments about your work, and be constructive.
By the time you've finished, you'll have gained practice in analysis and writing, hopefully kick-started your own work, and produced something which could be very helpful to the author, cast or crew. Authors always need reviews, so even if you only write a sentence or two and given them a star rating, you'll have produced something useful. Knowing that you've done that is sometimes all you need to relax and unlock your creativity.