Hello @similar2similar 
As @tatiang mentioned, please be sure to check out our posts about How to ask Great Questions v2.0 and our Community Guidelines as you get started.
Regarding the issue, maybe the Data source connection was revoked or expired.
To reset the Google sheet connection you can follow the steps here: Google Sheets Data Source - Thunkable Docs and for Airtable here: Airtable Data Source - Thunkable Docs