Probable issues and solutions after loss of certificates

First of all you should give an open advertisement through a lawyer in local newspapers both in English and vernacular language. Then by having an affidavit attested by a lawyer (maybe the same lawyer), you can approach the respective education certificate issuing authorities such as High school / higher secondary board, department of technical education (for your diploma) and university (for your degree) for duplicate copies of certificates. It will be easy to have the duplicate copies if you have any xerox copies of the originals you lost.

I think you might have already given police complaint and they might have given you a certificate saying that they are not able to locate them. Then only duplicate of original certificate will be issued. So you need not worry.
Nobody can use those certificates for any purpose. These certificates will have your signature as well as your photograph also. So they will never be useful to anybody. If you want you can give a paper announcement saying that you have lost the certificates and you obtained duplicate certificates from the concerned authorities and hence the original certificates will not be valid and no person can use them. You can give in one English national newspaper and the other one in local language paper and keep the paper cuttings with you. This is just a precaution and nobody can use them.
Your duplicates will be as good as originals and you can produce them for any certificate verification process in your job attempts. No problem and no body will object for this.
Don't keep this in your mind and prepare well for your examinations and job trails. All the best to you.

First of all, you have to approach police station of your area apprising them of having lost all your original academic certificates of class ten, twelve and diploma courses even though you have procured the duplicate ones. This is essential for your safety purposes. The police personnel would try to locate the original ones though sometimes it would not be possible for them to trace out the lost certificates but making such reports with the police is for your own safety.
Now you can notify the same through the paper advertisement that you have lost the original certificates and even you have managed the duplicate ones in lieu of the lost ones. Such notifications are to be made in both English Leading Newspaper and a Local Newspaper for the wide publicity of your message. This is a step of your precaution.
Apart from that, you need not think so much taxing your mind for such a trifle issue. Even if your lost certificates are within the possession of an unauthorised person, he cannot make use of your certificates.