A mass m is gently placed on the end of a freely hanging spring. The mass then falls 21.3 cm before it stops and begins to rise. What is the frequency of the oscillation?

I found the same question (with a different length) posted on here, but following the steps of the answer provided is not giving me a correct answer. I have used every resource I can think of, and have tried this problem over and over, but I cannot seem to get the correct answer. Any help would be great!!