When you say that something is in a `state of disrepair’, what you mean is that it’s in very bad condition. It’s in a state of neglect. Repairs need to be carried out.
Example: “We haven’t had anybody living in the old house opposite ours for quite some time. It’s in a state of disrepair. ”
It’s also possible to say, `fall into disrepair’.
Example: The old library building fell into disrepair after it was closed.