as long as the project of the coin that you invested in still has good progress and products, then I am sure there will be many investors who will invest in the project and make the price of coin you invested will increase slowly, so if you are patient to hold for a long time then I am sure you are will get a lot of profit (provided that the project you invest in is still developing).
It is so important to choose the right coins or else this is what can happen when you do not do enough research then may lose your hard-earned money. Instead staying with top coins only is much better at times I feel it atleast when rise happens you can make money.