Hello saint1729,
I’m sorry to have to write again, no backup done, most likely no chance.
By luck you’re maybe working under Windows (which you did not mention as part of the requested information). There you could have activated ‘System Protection’ (it is part of ‘advanced system settings’). If so, you could maybe access ‘previous versions’ of your file with the file manager.
Take a minute to understand what kind of fileformat csv is. It is simple plain text. ASCii. It is not possible to store more than one sheet in it. That and a lot of other things calc would like to store in a file.
For the future consider to store more than one version of your file. E. g. by adding a revision number to the filename or a date. So you could also go back in history of this file in case something went wrong.
Cookievore