Carry forward of loss

Can losses pertaining to two consecutive previous years be set off in the 3rd year together in full. And what if one fails to set off the previous to previous year loss whereas the immediate previous year loss was set off in full......................but due to some discrepany the previous to previous year loss though having room to set the whole loss off was not set off................can the same be set off in the third year.....this is about a pvt Ltd company.