I just got a recent Minecraft update for the Xbox 360 edition, but now when I attempt to enter my previous worlds, the device freezing and disregards any further passage into that world. Is there any way that I can fix or reverse the outcome of the update?
It is possible to delete the update, however this will delete all updates to all games, and can therefore can be fairly dangerous and is not recommended. Even after doing so, you will still be unable to use your world, unless it has only been played on Minecraft version 1.0.0 (ie you've never updated Minecraft previously). Also, you will be unable to play on Xbox Live until you update.
To delete ALL game updates (again, not recommended):
Settings > System > Storage > [Hover over Hard Drive] > Press Y > Clear system Cache
If you choose to try this, keep in mind that you will be unable to play on Xbox Live until you perform the update again.