How are you? I'll step up and be the first to offer something to get you started. Prayerfully ask God to open up your understanding. You may very well have retained more knowledge than you realize. Then, listen to as much music as you can. Try to listen for the "progressions" in the music . . . when they go up, when they go down, when there seems to be a key change, etc. Make a lifestyle of listening to music . . . it must be IN you. Get to know your scales, practice them. Watch other musicians and ask someone to show you some of what they know. Now, that does it for the "you be a good piano-player" speech. Let's start you on chords that you can experiment with.
Sit at your piano / keyboard in front of middle C. Now play a basic stacked chord; that is, play CEG, which are the C, skip at key and hit E, skip another key and get G. Now with your left hand, thumb and little finder play two C's one octave (8 notes) apart. This is a basic C chord . . . get used to the "octave chords" with your left hand; you'll be doing a lot of this in gospel music. Play it again and hear the sound. Now play the same thing in your right hand . . . CEG . . . and move your left hand up one note, playing a DD octave chord. Hear the richer, fuller, more "textured" sound? This is a second, a chord often used in gospel music.
Enough for now. Experiment with triads (that's the 3-note stacked chords like CEG) and the octave left hand supporting chords. OThers will tell you more, so hang in there! 8O BBoy