keyboard problem about one of the key's not working

the problem is, i was playing a game normally with my arrows and suddenly one of the arrows stop working (the down one to be specific) first thing that came to my mind when this happen is just to go and fix it, i mean it's just 1 key after all it wouldn't take much money to fix, but the shop told me to change the whole keyboard, so i decided to fix it by myself and i figured out what is the problem is that white small thing under the key got cut off for some reason, so i want to ask can i replace this with another one of those white things from other key on my keyboard is it safe anyways?