-If one forgot to count the Omer at night, one should count anytime during the following day without the beracha. One may then continue to count on subsequent nights with a beracha. Shulchan Aruch w/Mishnah Brurah 489:1
-If one is uncertain as to whether he missed the previous day’s counting he may continue to count with a beracha. Shulchan Aruch w/Mishnah Brurah 489:8 see also Bi’ur Halacha {[email protected]/Matzav.com Newscenter}