How do I know if I have an employment discrimination case

I was offered a position with a company I was told by the supervisor that I can start on the following Monday.I was then contacted by HR stating that the interview went well and I was then sent extensive hiring paperwork to be completed scanned and sent back.I filled out and first sent to a file on my desktop then I sent it not realizing I had also sent an arthritis questionaire from a study group I had completed and was in the same file.a few days went by I did not hear back so I contacted HR they didnt respond I then reached out to the Supervisior he didnt return my phone calls I then called the company they continued to send me to voicemail .for the record to the best of my knowledge do not have any criminal record or any legal issues I finally recieved an email back from HR stating that they were going to continue the interview process I still never heard back I was laid off from my job and have been out of work for 6 months please let me know if there has been an injustice done