Cydia has been showing up empty, with no files today, due to a source file corruption. If you're experiencing the problem on your iPhone, iPod touch, or iPad we are going to walk you through how to fix it.
The fix is fairly simple as long as you know how to SSH into your iPhone. If you don't know how to do so check out our SSH Guide and follow the instructions to get you started.
Once you get into your iPhone as navigating to a few menus and then renaming a file. What you want to do is navigate to:
Once you get there you will see a source titled zodttd.list and you will want to rename it so zodttd.list.old. Once you do this go ahead and respring your iPhone or iPad and relaunch Cydia. Now you will have everything back to normal (minus the ZodTTD source for now.
Cydia's creator, Saurik, has Tweeted to try to go to "Changes" inside of Cydia and hit refresh and let it reload and all will be fine as well. I personally tried this several times to no avail. So go ahead and try either method and let us know what works for you.
If you have any other issues check out the thread dedicated to this issue in our Jailbreak Froums.