if you’re ever stuck, just write anything. If the lines don’t make sense together, that’s great. If it sounds nothing like what you’d normally write, great! If it’s not very good, great. just see where your fingers fall on the guitar or piano, or where your wandering mind takes the melody and lyrics and finish whatever crap you’ve just come up with. Finish it in 20 minutes knowing you might not show it to anyone.
Sometimes you might end up finding a cool melody, lines or chord sequence that you fuck with, sometimes you won’t. But working from something’s better than nothing. You could sample it, repurpose it, trash it but you’ve got something tangible in front of you.