When HR completed its investigation, they should have let you know whether your allegations were substantiated or unsubstantiated. HR does not necessarily have to let you know what specific actions they took, if any, for reasons of privacy. However, if your allegations were substantiated, HR should at minimum tell you that the situation was handled appropriately.
Look at the company's policy on investigations and see if they outline their policy on investigations regarding closing out complaints. Through email, consider asking HR for clarity regarding whether your allegations were substantiated or unsubstantiated. You should have also been advised regarding non-retaliation.