Backdoor locks from the inside, but not from the outside.

[Kasay Mardis]

Hello again,

Our tenant claims she believes her back lock was vandalized by someone putting something in her lock preventing her from putting her key in it.  Prior to this she previously mentioned she doesn't use the back door, because with her back she can't walk down the small hill on that side.  Should I replace the back door lock even though she doesn't use the back door and it still locks from the inside?

Thank you