Sometimes it feels like you’ve either run out of ideas, or you have an idea but you’ve got zero motivation to work on it.  This is especially prevalent if you work on a large volume of games – like if you’re participating in #1GAM, or during a game jam.
I think these slumps are normal to the creative process, as long as they don’t stick around for super long.  Everyone has an ebb and flow to their creativity and it’s okay to have a dry spell.  Here are some places I go if I want some inspiration and motivation.