iac won't fully start up
I have an iMac 27" that won't start all the way. it gets to the end of the progress bar and stays there. When I attempt to reinstall macOS it tells me there is not enough space on the HD. I know there should be plenty of space on the HD so what do I do? I don't have a backup , yet don't want to loose my data. what do I do?
iMac 27″, macOS 10.15