I hear where you're coming from. I have the same things happening to me. It comes and goes but lately seems to be lasting for longer periods of time. I don't have any "solid" advice that I've tried and I guess since I read your post that I'm better at giving advice to others than actually seeing it when it's me.
I would try to write anyway. Set a time daily or weekly where you are suppose to just sit and write. I do this sometimes and literally just write single words expressing my feelings on a second by second basis like a flowing thought journal. I am actually a very good writer (or I was/ am sometimes) so I know it can be difficult to accept when you can't flow, or write like you used to.
Another idea I have is to keep a chart that you have to fill out about your mood and daily activities. Those things (when i actually do them) actually do seem to help, if even for a day or couple hours.
Lately I've been immersing myself in cleaning, my house is a mess because of my lack of motivation and somehow my mind has gotten to a point where once I start cleaning i become immersed and when I'm finally tired of it it feels like I accomplished something.
I don't know much about your symptoms or where your at mentally but these small things just to accomplish ANYTHING brings some of a "real" feeling back into my life.
I also just took mindfulness classes and I what I got from that is that you have to take time purposefully to reflect on "small things", like wow at least I have a bed to sleep on or I like the way I did my nails/hair whatever it may be.
Hope you find what you need to get right again.