If Crono detects an issue with one of your integrations, a banner will appear at the top of the app alerting you to review your Email or Chrome Extension connection.
From the banner
If you see the banner:
Click Settings on the banner. This will take you directly to the Integrations page to review and fix the issue.

From account settings
You can also verify your integrations at any time by following these steps:
Click your profile in the bottom-left corner of the app
Open Account Settings
Select the Integrations tab
What you can do here
In the Integrations page, you can:
Check the status of each integration
Reconnect integrations that need attention
Connect new integrations if not yet configured

CRM and Calendar
The banner above calls out Email and Chrome Extension, but the Integrations page is also where your CRM and Calendar connections live, so you can check and restore those from the same place.
CRM
Your CRM connection is under Account Settings → Integrations → CRM. If it needs attention, reconnecting means going through the integration flow for your provider again. The full setup steps are in How to integrate with Hubspot and How to integrate Salesforce.
Keep in mind that the CRM integration is requested by a Subscription Manager, and once it has been requested every user has to connect their own CRM environment. A colleague being connected does not mean your own connection is already in place.
Calendar
Your calendar connection is under Account Settings → Integrations → Calendar, which is also where a calendar is linked in the first place, using + New. The full setup steps are in How to connect your Calendar in Crono.
A calendar connection can become invalid — for example, if the calendar password changes, the connection is invalidated and must be re-authenticated. Disconnecting or deleting a calendar does not delete events already in Crono; it only stops the sync.
Once you review and update the required integration, Crono will automatically reflect the new status.