If one is no longer counting the Omer with a Brocho can one still recite the Ribono Shel Olom prayer?
I assume that you are referring to the paragraph that appears in most siddurim following the actual counting. This is an additional / optional paragraph that is not part of the essential mitzvah of counting.
Additionally, part of the paragraph references one of the Kabbalistic "sefirah" terms related to that day. The point is, that each day, there is a mitzvah to count, with or without a bracha. If you count without a bracha, you still fulfilled the mitzvah of counting that day. The saying of the vracha is contingent on the concept of having "temimot" meaning "full", "Complete" or "unblemished", and since you missed a day, you've lost the completeness, and cannot say the bracha. But, obviously, you still can and MUST count, daily.
For either of these two reasons, you can recite the Ribbono shel Olam following the counting.