Can you not sign in with a different device and still have the files from before? I had to reset my iPad and now I loged back in and only one of my files are there? Any help is appreciate. This is on Adobe Reader. Do they need to be saved to the cloud? If so how?
If you don't save the files to the cloud, they are only in the device. They are lost if the device is lost or reset, or the app is reinstalled. It's your choice whether to save them to the cloud. If you look in the app under Files you see the locations clearly: On this phone, in document cloud, somewhere else... you can click on the menu for any file in the device to send it to the cloud.
If you reset the device you should also be able to go the last device backup you took before the reset.