Does your virginity come back if you get amnesia? If you were a virgin and transmigrate into a person that wasn't are they a virgin again? What if it's just been so long you forgot how it feels?
That thinking makes me puzzle.
Losing Virginity making physiological changes in women body, there it's not that it can come back, regardless of amnesia.
For young boys it's different. While body may not change once or twice. Mental state may be different.
For isekaied "having middle age perception " making me think them as non virgin. If such person gets amnesia after they must surely be virgin.
Those very less experience, if they are celibate for long time enough to forget about it, I think their mind will truly become like virgin: full of bubbly feeling, full of tempting feelings and extreme attraction.