Best bet at this point would be to call or write a letter the executive offices in NYC and beg forgiveness. Tell them that in exchange for reinstating your MR points you'll agree to keep the card open and give them $X amount of business for the next 12-24 months (whatever you think you can commit to).
Good luck...
American Express Company
Executive Offices
200 Vesey Street
New York, New York 10285
212-640-2000
Executive Secretary's Office
212-640-5583