I've had this trouble for quite a while now. I'd always have these grand compositions suddenly popping into my head every now and then, but when I sit down to start playing, I feel this block. Sometimes I'd play the wrong note and everything will start to be in a mess.

Is there anything that can help? I will appreciat

I can't tell if you're assuming these "grand compositions" are your own inventions or not, but music that "pops into your head" is music you heard somewhere. It is certainly possible to compose mentally, but not without knowing what you're doing and not immediately. Real compositions don't just magically materialize; they require actual cognition: thinking. There's no "popping".

If, on the other hand, you're not assuming these "grand compositions" are your own, there would seem to be two choices: You could find out what they are, track them down, and get hold of the printed music or you could get better at ear training. The latter will take a lot of practice over a period of years and will be aided by a thorough understanding of music theory.