At the very start when I learned my first language. Didn't know where to find the "{" and "}" keys on the keyboard. Thought I would never be a dev, since I couldn't write a program without those keys.
Or when I didn't understand the notation of accessing values inside an array. Thought things like array[0] would do some magic to the array and didn't know how to access other parts of an array. I was following a book back then.