I don't think I've ever thought "I was wrong." That I have, on occasion, changed my mind about something doesn't mean I was wrong.
When I was in high school, my two best friends and I frequented a non-chain record store with a huge inventory of stuff you'd never see in Music + or the Wherehouse. When there was nothing new out from an established band, we'd often buy something we'd never heard of and then share with each other. One of my friends bought Ride the Lightning. He loved it immediately and we'd listen regularly on our commute to school. I hated it at first -- mostly because of James's singing. Sometime after we graduated (June 1985), I heard Creeping Death on the radio or in some other context and thought, "hey, that's not as bad as I remember." I borrowed RtL from my friend and completely changed my mind.
The other thing that isn't quite on topic, but about which I really was wrong was after I got my first stereo unit for my birthday in October 1981. It was one of those combo units with a turntable, a cassette deck and an 8-track player. I joined the Columbia Record and Tape club and selected 8-track as my preferred format. I don't think I ever got another 8-track after I got my initial seven albums for a penny.