Yes, if the seat is vacant then it converts, also the session is aleardy over but generally you can check the criteria for the same below -

3% seats are reserved on horizontal basis for Physically Handicapped candidates (only for locomotor disabilities of lower limbs between 50% to 70%, provided that in case any seat in this 3% quota remains unfilled on account of unavailability of candidates with locomotor disability of lower limbs between 50% to 70% then any such unfilled seat in this 3% quota shall be filled up by persons with locomotor disability of lower limbs between 40% to 50% before they are included in the seats of respective category) in 15% All India UG quota seat.

Hope this helps!!!