Hi @Wenying do you mean blind holder like window blinds? Mine get broken all of the time as I'm not being high quality blinds and they can only take so much pulling up and down. I simply replace mine, as I consider this to be normal wear and tear.
If you are trying to get a guest to pay for damages and didn't accept the resolution request, the only thing that you can do is escalate the resolution to Airbnb, and they have the final say. If they also deny the charge, then you have no other option than to repair or replace the blind holder yourself.
Good luck to you.