All apps, music, and playlists are now missing
All of my apps, playlists, and music are now missing from iTunes. The iTunes songs I purchased are also missing and have icons showing they are available from download from the cloud. I'm logged into the Apple ID I've been using all along. I have not upgraded to the newest iTunes yet--my program is the version from just before the recent upgrade. I have not made any changes to the program or my computer in a while, so I'm not sure what caused everything to disappear. The music is still in my iTunes folder where it has always been but it doesn't show up on iTunes. Has anyone else had this problem happen recently? I'd appreciate any help to fix it.
iPhone 5s, iOS 7.1