What To Do When Medicare Card Is Lost? 
If a Medicare card is lost , it can be replaced in one of the following ways : 1 -RRB- Log into your MyMedicare.gov account and go to the section that says Medicare Card Replacement . It will walk you through requesting a replacement that will arrive within 30 days . 2 -RRB- Call your local Social Security Office or call Medicare at 1-800-772-1213 . They will give you temporary proof to use until you get your new card in the mail . 