Try walking close to the wall; the bear may not show up if you are too far away.
If that doesn't help, go back to talk to Janus again; discussing the bear a second time may trigger its appearance.
Are you checking in the right spot, in the hall outside Janus' room, by the west wall? See this Castle Stormfist
screenshot.
What version of the game do you have, and are you sure you downloaded the correct patch? The patch checks the registry for the install path, and will give an error message if it does not find the expected information (ie perhaps due to a system restore, or an over aggressive registry cleaner).
Some re-release versions of the game may already be updated to the latest 1.0034A version, as shown in the bottom right corner of the main menu, so would not need to be patched. The DVD version is already updated, and the patch (designed for the CD version) should not be installed.
Anyway, there is a way to create / fix the registry entry that the patch is looking for. This is described at the end of the manual install description in the
Troubleshooting Tips topic. Alternately, you can email Larian support to get a vbs (Visual Basic Script) file which will do the same thing but is much more user friendly.