The explanations that chiropractors have for how it works are basically pseudoscience. It is for the most part a placebo (they pretend to fix alignment issues that just don't exist). But I'm not denying there may be instances where they actually fix something which could've been fixed by physical therapy as well. It's a dangerous gamble though, there are cases where people got paralyzed or outright died because of a chiropractor. This is a good overview: https://www.skepdic.com/chiro.html