After Harry had contacted her, Lily decided that she would go and check on Severus in his apartment. It wasn't like him to not go to work. It wasn't like him to not respond to anything. The one time he'd done that, it had been because the Teseract had taken him back -- or so they'd thought. Really he'd just been apparently doing secret things no one could know about, and so they'd all been told he'd been taken back. She somehow doubted that was what had happened this time, and indeed it might be likely that he'd been taken back, and Lily really didn't want to contemplate that possibility.
She tapped her foot impatiently as she waited for the elevator to take her to Severus' floor and then she quickly went to the door of his apartment. She stood outside for a moment uncertain what she would do if he didn't answer, but then again, if he didn't answer it didn't necessarily mean he was returned home - just that he wasn't at his flat. There was no need to worry and create problems where none might exist.
She took a deep breath and calmed herself before she raised her hand to knock on the door giving it a moment before calling through the door, "Sev?" Perhaps she wasn't as calm as she'd managed to talk herself into believing she was.