Decryting old files

So for about 6 months I had been using nextcloud on a sbc. It was a odroidxu3 lite with 2tb external on ubuntu. The os is on a 16gb emmc chip, the default storage is set to be the ext hdd. One day my os starting getting messed up, couldnt fix it kept making worse. Its at the point of whiping the OS and starting over, But my files are encrypted. I have the standard encryption module on as well as the end-to-end encryption. What do I need to do with my filles in my data folder, so theyre functional in the new installation.