Hehehehe, this usually happens and writers complain about it all the time. I'm something of a writer so I experience this too and I've come up with some tips that help.
Two things usually make one unable to write, they are: (1) weakness due to stress or sickness and (2) lack of ideas.
For the first one, simply treat yourself, rest, rejuvenate and stuff. For the second one, it's usually best to consume content about the things you're interested in and soon you'd come up with ideas for writing yours.😊✌️