@SarahGen-- I'm guessing that you have a natural hair wig?
Wigs are prone to tangling because normally our scalp produces oil which naturally conditions and protects our hair. But with wigs, that's not possible. Many wigs have also been processed and dyed to different colors so they are damaged..
You have to moisturize your wig more than you do real hair. For this, I suggest doing hair masks with natural oils like coconut oil, jojoba or argan oil at least one to two times a week.
Each time, leave the oils on for at least half an hour and then rinse. This has worked very well for my wig. It rarely tangles now.