If you or someone you know has trouble reading music, regardless of the reason, take hope! Some of the greatest musicians could not read music. Being able to hear the music, and putting in the time, energy, and training to understand how to replicate and produce it via your voice, an instrument, or other device is, in the end, what matters. Does that mean some pieces, which are complex and lengthy, will require some serious memorization? Sure. But the brain is amazing, and with training, time, and focus, you’ll be amazed at what you can submit to memory.
In regards to personal creativity, though, lacking the ability to write music on paper via the traditional methods is not a deal breaker by any stretch. Those aren’t the only ways of getting that amazing melody playing through your mind recorded. Today, more so than ever, we have the ability to record ourselves as soon as a melody pops into our heads. Sing it, hum it, play it, whatever, just get it out and then get to work.
Here’s a great article by Tom Barnes at mic.com discussing this seeming limitation and those who not only overcame, but flourished.