I've been writing code for 15 years and I definitely experienced what you mention - but changing the topic made me find my passion back. Sure, sometimes I was depressed, sometimes I had enough and wanted to follow some other passion outside of coding, sometimes my eyes wanted to give up - but if I'm healthy and the problem is interesting, I can still get stuck to the creative process.

My dad has been a developer for 40+ years and he stills get excited about random, incredibly complicated projects (that don't even pay that well) or new technologies.

Maybe you just need to find something else you enjoy coding.