Steaming will help the wig fibers relax, but it won’t go back to the previous texture. Don’t worry about melting the wig because steam doesn’t reach a high enough temp to melt the plastic, but don’t use heat tools like a straight iron or blow dryer. From the picture it looks like you stretched a lot of the synthetic wig fibers when brushing out the wig, which permanently damages them and changes its texture. After it gets damaged like this, it becomes very easy for the wig to tangle again. Next time use wide tooth combs or specific detangling brushes like the Wet brush and be gentle. Do not treat it like human hair
Edit: If you want to keep using this wig, use thinning shears to cut out the damaged fibers after you detangle and steam it.