Which form of birth control could people use without altering hormonal systems or blockin sperm from fertilizing an egg?

Fertility awareness aka cycle tracking.

can also be surgery but that does technically alter hormone production.

light rays enter the eye through the cornea, the clear front first understand how the eye enables us to see, and what role the cornea plays in eye at different angles, and do not focus on one point the retina, but on many we can tolerate very large scars on our bodies with no concern except for our vanity.