to the OP - don't sweat it. i shot 40 and 43 on the front 9 of my muni course the last two times i played. I went to the range, hit everything perfectly! i'm talking deadly accuracy with every iron, 300+ drives dead straight.
I got to the course, parred the first hole, had a lost ball on the second hole par 3, hit provisional, thought i found my first ball, played it, got to the green realized it wasn't mine but had already picked up the provisional, replaced the provisional played it to a 5 (which technically isn't legal anyway because i picked it up already). then FOUND My first ball after holing out, played it to a bogey but knew that the hole was basically ruined. Everything fell apart after that. got a 9 on a 130 yard dead straight par 3... was in the woods the next few holes, then for a grand finale, I pounded 7 balls with 300 yard slices DEEP into the woods - couldn't get a playable tee shot. got a 20 on the 9th hole.
it happens to all of us.