Generally, elevators have emergency call buttons. You could use that button to get assistance in getting to your destination.
If this does not meet your needs, your next steps will likely depend on how often you use this particular elevator. If you use the elevator only rarely, consider asking for help from those around you to locate building staff, like a security guard, employee, or building manager. When you speak with building staff, explain that you are having trouble with the elevator because of your sight loss. Explain what assistance you require in as much detail as possible.
When you disclose your disability to an employee, you trigger that organization’s legal duty to accommodate you to the point of undue hardship.
If you use the elevator more frequently, consider contacting building management directly to explore options for ongoing accommodation. If this does not help, you can escalate your complaint; for example, through an official complaint process or to an organization’s management team. Many governmental organizations and large private companies have a designated person responsible for site accessibility.
For additional options, please review the section of this handbook, titled How can I enforce my rights?