Jesus christ, man... That's going to take a year to correct. Have you never once scrubbed your feet?
If you can find one, get a bar of soap that has lavender essential oil in it and a rigid nail brush. Every single day in the shower, scrub the fuck out of those things using the soap. You're only going to kill 99% of the fungus/bacteria so it's important to do this every day. Once the infestation is in check, your body will naturally grow out healthy nails but it takes a while.