You can order a replacement SIM in "my o2" (if you are registered there).

Hallo,

Thank you for your reply.I had ‘My o2’ account for sim number but unfortunately now I can not log in. it says due to entering wrong passwords it is blocked.

Hallo @jj_rod ,
I’m sorry to hear about your stolen phone.
But do not worry we are happy to help.
Would you mind sending us a private message to @o2_Support with the phone number of your stolen sim-card? Unfortunately the email address you are using here in the community can not be linked to your account. So please send me your PKK (the 4-digit private customer code you created at the beginning of our contract) and the phone number of your simcard, so that we are able to send you a replacement and block your old one.

But if it is super urgent, I would recommend to call Kontakt aufnehmen und Hilfe finden | o2 (o2online.de)
 

Best Matea

Hey @jj_rod,
your number was blocked successfully
Did the solution to your further question by changing your password in Mein o2 (Passwort vergessen) or to seek help at your local o2 shop work?
Kind regards, Matea