do not say it again.
if the food or drink was not in front of you and was also not available to you when you said the first fore-blessing, say a new fore-blessing.
if you are not certain whether you had said the after-blessing and even if you definitely did not say the after blessing, do not say a new fore-blessing.
reason water is always considered to be in front of you (in the water pipe).
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 