what should i do if client send a unfinished project and i have spent much time on it?

hi,

i have spent much time to fix some important bugs in the project and am going to do next steps, the client suddenlly told me there is not important configuration data in the project, so the project will not finished successfully, so he want to cancel the project and refund all of deposit. But i have spent much time on it, so i don't agree to refund all of deposit. The client continue to request to refund all of deposit, what should i do for this case? Shouldn't he be responsible for the time I spend?

Thanks