It may not be possible to give you a complete answer without seeing your lease, and how it set forth the procedure following expiration of the lease. Did you receive a signed renewal lease back from the landlord? Did you verbally tell the landlord that you would renew the lease on the terms in the renewal lease? You may not have a valid lease contract - or you might. It depends on the facts. Even if the landlord can show that he has a lease with you, you might still be able to break it without penalty due to the mugging incident, although much depends on the facts. I would recommend talking this all over with an experienced attorney who can advise you what your options are based on the facts of your particular case, the terms of the lease, the facts pertaining to the mugging incident and the current landlord-tenant laws.
Dear I want to leave:
Perhaps I might suggest an answer to your question.
If you are a rent stabilized tenant, and you were offered a lease renewal and you do not want to accept the renewal offer, then check off the appropriate portion on the renewal form that you decline the offer. Follow the instruction on returning the lease renewal (declined) and make sure you preserve a copy for your records as well as proof of mailing. Your lease then ends on the scheduled last day and you move out on or before the last day. Or, move out earlier than the day the lease ends, as long as you followed the process to decline the offer of the lease renewal.
You may remain liable for the remaining term of the lease, as merely moving out does not end your obligation to pay the rent.
If you are not rent stabilized, and your current lease required a offer to renew, look at your current lease for the instructions about your right to decline the offer and to move out from the apartment.
The answer provided to you is in the nature of general information. The general proposition being that you should try to avoid a bad outcome if you can.