First of all dont panic.
I think the best thing we can do now is to wait.
Maybe the price of some altcoins will never recover. It depends on the altcoin.
panic is the most of things that we need to prevent because once we are panic, then we cannot think about what next that we should do and we only want to get out from the chaos. but I think, by learning how to control our emotion, we can stay calm when all coin is on dip and we can make another strategy to prevent the loss. and if altcoin is on the dip, actually, it is the best time for us to buy more coins because the price is really cheap so we can get much amount of many coins.