Situation You say the incorrect blessing over food in front of you but you also have a food in front of you that does fit the blessing.
What To Do You may eat the food covered by your actual blessing, and then say the correct blessing for the food you originally intended to eat.
Note You may not go into a different room to find food that qualifies for the incorrect food blessing. You should instead say Baruch shem kevod malchuto l'olam va'ed as soon as possible.
Note There is no specific time limit beyond which you may no longer say Baruch shem kevod malchuto l'olam va'ed.