If you are on iOS, to take your shop off of vacation mode, go to Settings (on your Profile screen), tap on My Shop, scroll to the bottom and tap on "I'm back! Show my listings." Here's what it looks like:
1. Go to your Profile
2. Go to your Settings:
3. Go to My Shop:
4. Tap on "I'm back! Show my listings.":
On Android, the steps are a little different. You simply go to your Settings and tap on Turn Off Vacation Mode.