Have you lost the YouTube app as well? I lost both the Netflix and YouTube apps.
If you try to switch to channel 661 (or whatever the Netflix channel is in your region), do you get Error Code V301 "App Temporarily Unavailable"?
If yes to both, then you would appear to be in the same predicament I am.
The first thing you can try (based on TiVO.com support forums) is a reset/reboot of TiVO (but NOT a reset to factory defaults).
Do this from the TiVO Central menu: Menu > Settings & Messages > Help > Restart or Reset > Restart Tivo Box then three ThumbsDown and Enter.
It'll take a few minutes to reboot, and then a while longer to load the guide. (This will NOT cause you to lose channel selections, saved recordings or OnePass setup.)
Then check again for Netflix and Youtube in the TiVO menus, or channel 661 (or your regional Netflix channel).
If still no luck, then you're exactly where I'm stuck.
According to TiVO.com support forums, my next step is to do a factory reset. That'll wipe out channel settings, recordings, and OnePass setup though, so I've got those noted to re-enter. Cogeco has been waffling on letting me do that since it'll unpair the CableCard and cause a basic setup of the box to be needed at their end too. If they don't come back to me soon, I'm going to do it and then call in and say, "It's broken!".