Here is what we know.
No one ever instructed OP to do her own filing, even before she was injured and asked for an accommodation. To OP's knowledge, no one else was asked by management to do their own filing. No one was asked to help the file clerk and no one was hired to assist the file clerk. Logically, if no one in management directed employees to do their own filing, the file clerk was expected by management to fulfill all of the functions of the job, without accommodation. The co worker who yelled at the OP took it upon herself to help the file clerk, and berated the OP for overburdening the file clerk.
Logical reasoning. Only one conclusion is possible. The file clerk did not have an accommodation .