Instead of the lost originals, study the texts that derive from the 64:
In Kaula Tantra, the texts are classified into: 64 Tantra Pdf
Attempting to read a "64 Tantra" without Diksha (initiation) is considered not only useless but dangerous. The texts often contain Bija Mantras (seed sounds) that, if mispronounced or misused, can cause psychological disruption. This is why Gurus hid them. Instead of the lost originals, study the texts
If a website claims to have the "Complete 64 Tantras PDF for free," close the tab. Genuine Tantra requires Guru initiation (Diksha) . It is not a self-help e-book. Many "DIY" PDFs online lead to psychological distress for unprepared readers who attempt the rituals without guidance. Attempting to read a "64 Tantra" without Diksha