What canI do if my public defender won’t look at my case and I can’t afford to hire a private lawyer?

You really don't provide much by way of facts. For instance, what do you mean that your PD won't look at your case? Are they too busy?  Anyway, under certain circumstances a defendant can receive the court's permission to get a substitution of their appointed counsel. While this is not readily granted, it can be done. There will need to be a hearing for substitution of your court appointed counsel.  That means that you can get a different public defender to represent you if you can convince the judge that this is necessary. 

To seek a hearing for substitution of counsel, you should write a letter to the judge, requesting a meeting with them regarding your counsel.  A copy should be sent to both the lawyer that you want removed and the prosecutor.  Make sure both copies and the original (which goes to the judge) are sent certified mail; you also need to keep a copy for yourself.  This letter should state that you want your present attorney removed from the case and why.  You need to list all problems that you are having with your attorney.  The letter should be kept short and to the point.  Be sure that it is truthful, you do not want to jeopardize your position before the judge by stretching the truth.