I was allocated a seat in Round-2 of NEET for Deemed University ,but i did not join the college and fee was forfeiture.

According to the official website at mcc.nic.in, the mop up round is conducted by DGHS for Deemed and Central Universities. In the mop up round the net vacant seats due to non joining, non reporting from Round 2 will be published in the seat matrix and eligible candidates will be allotted seats according to choice and merit.
Who are not eligible:
Candidates who have joined in Round 2 of Deemed/Central Universities are not eligible.
Who are eligible:
Candidates who are registering for the first time
Candidates who have registered but havent been allotes seats in Round 1 or Round 2
All those Candidates who are holding a seat from Round 1 or Round 2
If you haven't joined the allotted seat in Round 2 and have forfeited the fees, it is as good as you dont have a seat in hand right now which qualifies you to appear for mop up round.