There are a few excerpts from GOF and HBP that, in my opinion, undoubtedly prove that LV did not use a horcrux to regenerate. Here they are.....
GOF. Chapter 33 - The Death Eaters, pg 566 (english version)
LV to his Death Eaters
' ....I miscalculated my friends, I admit it. My curse was deflected by the woman's foolish sacrifice, and it rebounded upon me. Aaah... pain beyond pain, my friends; nothing could have prepared me for it. I was ripped from my body, I was less than spirit, less than the meanest ghost.... but still, I was alive. What I was even I do not Know.......'
GOF. Chapter 33 - The Death Eaters, pg 566 (english version)
'....I was as powerless as the weakest creature alive, and without means to help myself...for I had no body, and every spell which might have helped me required the use of a wand .....
I remember only forcing myself, sleeplessly, endlessly, second by second, to exist, I settled in a faraway place, in a forest, and I waited....surely, one of my faithful Death Eaters would try and find me... one of them would come and perform the magic I could not, to restore me to a body...but I waited in vain.....'
HBP. Chapter 23 Horcruxes, pg 470 (english version)
DD to Harry
' The seventh part of his soul, however maimed, resides in his regenerated body. That was the part of him that lived a spectral existence for so many years during his exile; without that, he has no self at all. That seventh piece of soul will be the last that anybody wishing to kill Voldemort must attack - the piece that lives in his body.'
LV did not die when the AK curse rebounded because of the horcruxes that he had made. When he was 'ripped' from his body, that part of his soul did not disappear into the afterlife (or whatever happens in JK's world), it was kept earthbound by his horcruxes. He was able to exist in spectral form, untill WT performed the complex magic to give him a body.
LV was 'less than spirit' because there was only a fraction of his soul remaining in his body, the part that he saved from death, by making horcruxes.
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