Hello,
The scenario that you mentioned above could happen with anyone. So, there is no need to panic over such situations. First thing that you need to do is that if it has lost within few days from now, then you can file FIR to the local police station or wherever you think if you have lost(only in the condition when you are certain about each details related to the missing of your original marksheet). But if you are not sure about when you lost them or the duration when you lost them is too long from now, then you can just contact RBSE education board by writing an application and mentioning your scenario. If they would accept this, then you may be able to get a verified marksheet which would be accepted by your college. Also before doing this try contacting the Principal of your school from where you completed your 12th because it would be a smooth process when a professional related to school would be involved in it as they would provide you all the details regarding your marksheet like registration number and all.
Hope this helps.
Good luck!!
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