Just keep holding your altcoins and dont sell during the market is down. Hold it for atleast one month or more. Dont think about your losses because its just paperloss and dont panic.
You will not lose more as long as you don't sell your altcoins. Set your selling price, go for your activities and have fun, come back in a few months, then you can smile again. You have to hold and be patient a little bit, it will get some time until the crypto prices increase again, but it will go up sooner or late