[sarcasm]Yes, Speedplay cleats magically align themselves onto the shoe to give the correct bio-mechanical positioning.[/sarcasm]

I think the OP had good cleat position, then one of the cleats moved, and he is trying to rediscover the position.
OP, I would start with putting the cleat center line (assuming that they are marked) underneath the ball of foot and aligning it in the center side to side and putting them straight.
Get the bike on the trainer and get pedaling about 5 minutes. If the cleat position is wrong you will be able to tell and also be able to tell which way the cleat needs to go.
The hardest for me is the side to side adjustment of the cleat (Q factor) and I normally go for a long ride and take my tools with me and adjust as necessary.
This is all assuming that your original setup was fine.

Good luck. And next time, mark the bottom of your shoes with a silver sharpie once you find a position that works for you.