Because my 2023 taxes were rejected, I need a copy of them. We are unable to find our paper cooy

Is your 2024 return rejecting or did the IRS ask for more info?  If you are trying to efile then enter 0 for the 2023 AGI or say you did not file.  

To file 2023 you need to print and mail it now.  How to Access prior year online returns
https://ttlc.intuit.com/community/prior-year-return/help/how-do-i-access-my-prior-year-return/00/27010

If you can't get the side menus to open up to access the prior year..... You need to start entering some basic Personal Info in 2024 for the side menu to open up. Just continue a little ways into 2024. I had to go though about 12 screens.

If you used the Desktop CD/Download program then the only copy is on your computer and not saved or stored online. So you need to make and keep your own backups.