I'm glad you sorted it out.
Can you detail here what you did? The more information you provide here, the easier it will be for others to help you figure out the problem. Also, this will be good for the community - if others come across the same issue in the future they may be able to solve the problem too :)
A few possible reasons this could have happened:
1. You had a region placed on a separate track assigned to the same channel - but had hidden the track.
2. You a separate track (assigned to a separate channel) with an UB inserted on it and it's sequencer was on - but you deleted it from the Arrange or hid it. However, it still existed in the Environment, so played the UB pattern whenever you pressed Play in Logic's transport.
3. The region wasn't muted.
4. The Logic project was corrupt (unlikely - but still a possibility)