It's been almost 4 years since I had too much time on my hands while living in student dorms so I decided to learn to play the piano.
I always loved listening to classical and suddenly listening wasn't enough so I decided to start playing. I had really A LOT of free time, so I'd often sit for 8 hours straight without getting tired and couldn't wait to pick up where I left off the next day. Maybe it wasn't quite the smartest thing to do, but I started with a Chopin prelude (4th, the simplest) and raised the bar from there. In my defense, I never had delusions of concert-level mastery (I was 24 back then), just wanted to have some fun with my favourite pieces. It toook me months to pick up a new one but I didn't mind, the reward of a few bars of something I really loved was enough.
As time went, I got a little better. Having had little in the way of musical education (some recorder in primary school which I enjoyed a lot), I relied on occasional bits of insight from my roommate who was a fairly good musician (accordion, also decent on piano), the rest I picked up from books and Wikipedia. I learned the Raindrop prelude by Chopin, some time after that the Military polonaise, got even as far as the op10no12 (revolutionary) etude. Sometimes I gathered the courage to play at some venue and it gave me great pleasure when I'd get claps and occasional praise from more seasoned pianists, but not as much as I had from the knowledge that I knew how to play my favourite pieces and even play around with them a little (tempo, expression etc.).
Then things started to get complicated. I had about 20 pieces in my modest repertoire when realized I couldn't play the 4th prelude anymore, so I worked to get it back together. Then I developed problems with parts of other pieces I thought I knew. Everything started falling apart. Suddenly I realized I was just a trained monkey who learned how to type the works of Shakespeare without knowing language. I still don't know how I really remembered those pieces. It can't all be muscle/visual memory, can it? On the recorder, it was simple to play things by ear and my friend said I'd eventually 'get it' on the piano so I patiently kept playing and waited. Then I got really depressed and stopped playing for about two months. Every now and then I'd sit and try to play a Bach variation or something else, but I'd just get in despair at how it'd break apart. All the joy was gone.
I tried to begin anew, but this time simpler. I would listen to some simple pop music I liked and try to play it (sometimes with the help of chords from the net). I was determined to make it work, but after a two weeks' break, I can't remember how to play those pieces either. I wish I could just sit and play something I hear clearly in my head, but I just can't. Any advice on how to make this happen?