So sorry for your loss. It is likely that the bird that died had been ill for a while, birds are masters at hiding illness. Therefore you need to keep a very close watch on your other bird for any signs of illness. Some birds do ok as a single bird it depends on the individual bird, is the bird at all tame and how much time do you spend with it? If you do decide to get another bird you must observe quarantine rules, this means keeping the birds in separate cages in separate rooms for 30-45 days. It would also be a good idea to locate an avian vet in case something comes up in the future that needs attention. You can do a search in this link by entering your country in the appropriate filed https://www.aav.org/search/custom.asp?id=1803