Misplacing of original 12th std marksheet and leaving certificate

Hello sir, I had taken admission in degree college in 1998 by submitting my original 12th marksheet and previous college Leaving certificate in year 1998 (commerce stream )in Thane district. I appeared for Tybcom exam in 2001. But my 01(one) subject was not cleared. And I didn't appeared again due to my father expired within month of result. And for financial reason I couldn't appear further till 2016. I cleared my exam now; and demanded my Original marksheet and Leaving certificates original back from college to continue my further studies in Law. But they say now that it has been taken or misplace by them self. When I told them show me my signature of receiving my original documents. They turned their statement and said it has been misplaced. Now Sir, how could I get back my all original papers without any time spending as my future studies deadline are coming close. Or please provide me some solution so that I don't miss my academic year. Please help me ASAP. Thanks Adi Jijina.