docs: explain gaps after logging stops

Add a focused FAQ entry directing users to logs first, covering token renewal without data loss, and explaining when missed drives or charges can be imported.

Author: Magrathean UK

website/docs/faq.md

@@ -10,6 +10,14 @@ There are multiple apps available to securely generate access tokens yourself, f
 - [Tesla Auth 0.13.0 or newer (macOS, Linux, Windows)](https://github.com/adriankumpf/tesla_auth/releases/latest)
 - [Auth app for Tesla (iOS, macOS)](https://apps.apple.com/us/app/auth-app-for-tesla/id1552058613)
 
+## TeslaMate stopped recording data. How can I fix it?
+
+Check the TeslaMate logs first. They usually show whether TeslaMate cannot reach Tesla, cannot connect to the database, or needs new credentials.
+
+If the logs show an authentication error, use one of the tools above to generate a new access token and refresh token, then enter both on the TeslaMate sign-in page. Signing in again does not remove data that TeslaMate has already recorded.
+
+Tesla's API does not provide historical drives or charges, so TeslaMate cannot recover data that was missed while logging was stopped. If another supported logger recorded the missing period, you may be able to add it with the [TeslaFi import](import/teslafi.md).
+
 ## Why are no consumption values displayed in Grafana?
 
 Unfortunately the Tesla API does not return consumption values for a trip. In order to still be able to display values TeslaMate estimates the consumption on the basis of the recorded (charging) data.