I've seen this come up in my own code and it's a popular question at StackOverflow. The usual culprit is that the UITableView's dataSource or delegate aren't set. Check your connections in Interface Builder or in your code.
If you have a UITextView subview on one of your cells that for whatever reason doesn't resignFirstResponder, the calls to reloadData won't work. You can reloadRowsAtIndexPaths for those cells that need to be updated.