All of my messages are gone after restarting my phone!

Hi all. So yesterday I was using my phone and it was lagging a little, especially with Snapchat (although I suspect that was because of a Snapchat issue, not my phone). And so I restarted my phone. But then, all my text messages had disappeared! I tried restarting again twice after waiting a couple of minutes, but nothing really worked. However, Messages still uses up the same amount of storage as it had before, and when I try searching for specific text threads, there are no results. Then, my photos started disappearing. I'd wait a few seconds, and some would come back, but then the app would crash all over again. I turned off my phone and waited about an hour before turning it back on. Well, the photos were back, but the messages weren't, and they're still taking up about 1.5 GB of storage! The day before, I had downloaded the 9.2.1 update, but I was unable to install it for some reason, and I feel like this might be connected to the deleted messages issue. Today, I connected my phone to iTunes and installed the update from there, but my messages are still nowhere to be found. I have an iPhone 5S, and it is in very good condition. Please help me!