My 16 month old has not had a wet diaper in 24 hours. she has been drinking normally and acting normally. no fever or anything. should i be concerned?

Yes: She should be seen right away if she has not wet a diaper in that period of time. Especially if she is drinking and eating normally and not having vomiting or diarrhea as a source of fluid loss. If diarrhea, you may miss urine in diaper mixed in. Please have her seen by a doctor and get her checked for kidney function and to see if her bladder has urine.