There are a few reasons why a sequence might not be sending emails that you can check:
The Status of the emails in the sequence is still Draft
The "When to Send" field is set to the future. You'll find this in:
- The settings for each email or
- The settings for the entire sequence
The filter on the emails is filtering out people who should be getting the emails. You'll find this in:
- The settings for each email or
- The settings for the entire sequence