Listed below are some organizations working to preserve access to data that may be important for physics research.
For more information about these efforts, explore the Data Rescue Project, a coordinated effort among a group of data organizations, including IASSIST, RDAP, and members of the Data Curation Network, with a goal to serve as a clearinghouse for efforts focused on preserving access to public data and data access points for public US governmental data that are currently at risk.
If you are looking for a specific dataset, check the Data Rescue Project Tracker.