Have you just updated the software on your tablet? Have you installed any new apps when this started happening?
I'm wondering if a factory reset may be in order, but hopefully we can solve this without doing that.

 

You should be able to go into Settings - Backup and Reset and then Factory Reset.
Be sure you know EVERYTHING will be erased from your tablet. Backup anything you want. Google should have your contacts and apps backed up (but not data).
An app like Helium should be able to accomplish all of that.
https://play.google.com/store/apps/details?id=com.koushikdutta.backup

 

You could try a different launcher. I had a similar problem once. There was something wrong with Touchwiz. There are a bunch at the Play Store. I really liked Go Launcher. If your problem is Touchwiz, that would solve it. You would have some set up and a small learning curve, but lots less work than a factory reset, and Go Launcher adds some features.

 

I'm so sorry. I'm not familiar with the factory reset process so I don't know what to say about the password thing. Hopefully someone more knowledgeable will chime in.

 

Similar thing happened to me yesterday. An app started crashing where it never had before, after restarting I got prompted with the initial tablet setup and various apps no longer worked due to the same crash on launch behavior you get. The play store link on my home screen gave an "app not installed" message and it was replaced in the app lists by the old android market app.

Updating the android market app reinstalled the play store app. After that I found this post so I installed go launcher and confirmed that didn't fix the issue. At this point I checked a few apps to see which were stuffed. The affected ones seem to be those I used recently before the crash.

I tried uninstalling one of the stuffed apps and it worked fine after I reinstalled it. Tried reinstalling two others since then and both work again. I hazard a guess that during the initial crash that caused the issue various apps that happened to be in the cache at the time became corrupted.

Try reinstalling one of your apps and see if that resolves it. Even if it does you still have to worry about losing your data and settings on a per app basis, not to mention any default apps that can't be uninstalled without rooting or any system internals that may now be messed up.