I have not been on Scratch for a very long time and only just returned to it yesterday, so I may have forgotten how to code. But anyways a long time ago, I remixed a project, and changed some costumes. That's all. My computer is, however, very laggy so when I tried to edit a bit more today, it froze, and when it unfroze nothing seemed amiss, but I think I accidentally changed some code. I clicked the green flag and the way it works is that you move the character with arrow keys, but when I press them they don't do anything. The link to my project is here: https://scratch.mit.edu/projects/54040988 . I know that it is not a problem with my computer because although I am using a new one, I went to the project mine is based off and it was working fine.

Thanks in advance.

You've either added new costumes or changed the order as the movement script for the cat sprite only moves if the costume# is between 1 and 6. The cat's costume# is 12 so doesn't move. Always a good idea to look at a projects scripts and understand them if you can.

Thanks! I reordered the sprites and got it working again