Help with stained leggings, please?

At work last week, I apparently stained one of my favorite pairs of leggings with...something...I don't know what it is, I just know that it isn't coming out! I think it may be bleach. Anyway, this happened last week and I don't know what to do from here! I really don't want to throw them away, because I can't seem to find them anywhere else...

Is there any way I can get the stain out? Or cover it and blend it? Something else? Any help would be appreciated. Thank you!