I have first uploaded several audio files while creating new Post through Add Media function. I decided to try uploading files through FTP and uploaded several audio files through FileZilla. I uploaded them to the Upload folder in my WordPress directory where I found files I uploaded earlier through the add Media. Now when I try to add these to my Post through add media it doesn't show them in the Media Library or elsewhere though I can see them through File Manager. Is there a specific folder I need to upload media files to to be able to access them through add Media function?