Score went well below PR (your weaponry is too strong for your char at the moment, see
Weapon Allowance.) and you should've gotten a warning e-mail letting you know your char was to be retired. You can unretire the char after 4 days and before 9 days after its retirement via the manage characters link below your character dropdown list. Or you can send 50k to
Charity and have an admin unretire it at any time.