Manifestation / LoA is real and works 24/7 all the time and automatically.
But you are right that you were scammed by marketing people on how it really works. Abraham Hicks, Rhonda Byrne etc. are all scammers.
It is not about your positive thinking, visualization or what you even consiously do most of the time.
It is all about your Subconscious Mind and the feelings that the core beliefs generate 24/7 and that you carry with you.
Check out my various posts on manifestation on this forum (there are many) where I explain it in detail. Just use the search function.
I think this here is the most short summary:
https://forum.enlightenedstates.com/t/jaajs-daily-self-love-stack/27697/23?u=jaaj
Good luck!
PS:
Neville Goddard is actually really good and provides very good and proper manifestation advice.
PPS:
Start with trauma healing.
Then with increase of self love.