I am a Ghanaian, currently in India for study, but have lost my Italian residence permit card. I asked a friend what to do, and was told to report the loss to the police with a photocopy of the permit, which I don't have. I do have my Italian school results; could that be of any help?
Your question suggests that you were in the country as a student, and your residence permit would have been associated with that visa status. The validity of your residence card would have been the same as was indicated on your visa. As a non-EU national, you cannot simply replace the residence card, and cannot do so when you are no longer in Italy. Should you still have a valid Italian visa and plan to return to Italy and remain for more than three months, you can apply, as you did previously, at your local Questura.