What's the time limit on filing a police report in California?

My foot was run over a little over a month ago. I didn't want to file a police report because it was a mutual friend and she said she would help with any medical bills. Now the bills are starting to come in an she's nowhere to be found. I have proof of my medical bills in the emergency room as well as 2 witnesses saying she ran my foot over. Is it too late for me to file a police report?
Please sign in to answer this question.