If you sold before the dump, then that is good, because you can buy back at a lower price, but if you sold during the process of the dumping (or near the low price point hoping for a lower low), then you may need to take a loss and buy back before the price get's too far above your sell point.  On the other hand, you could take a chance and wait it out, which may or may not pay out (despite being a bit stressful to wait out and hope for another dump, which is not out of the question at this point).