Okay, that is weird. It looks like your collection isn't really lost. Otherwise it probably wouldn't show up under "Browse". First check that you are in the right collection (probably "Owned"). With a lot of luck, you simply switched to "Ordered" or "Wishlist" as a result of the crash.

If that doesn't help, try to reboot your iPad. (Hold Standby and Home for several seconds until the Apple logo appears.)

If those two steps don't solve the problem, hope someone has better ideas.

And then there is the radical method:
Every time you sync your iPad with iTunes, you create a backup of the contents of your iPad. You could do this:

- delete iPad
- plug iPad into your computer
- restore from backup

Now everything should be as it was the last time you synced your iPad. Obviously this only works, if you regularly made backups. If you only plugged the device into your computer once to activate it or didn't back it up recently this won't be any help.

Get the free desktop version, sync your database and perform a database repair. That might help with the crashes.

Also completely close the app (remove from multitasking bar) and reboot the iPad.