What's the matter that all the information points in March in iphone6 SMS are empty? Can you get it back online?

Maybe you set the message to be saved for 30 days, so the message from last month will be gone. You can set it back to "permanent" according to the following steps, but the erased information can't be retrieved, and it's very troublesome to bring it out, unless you find the telecom backstage and the public security bureau and have special circumstances and relevant certificates:

Information was found in the settings;

Click "Keep Information";

Select "Permanent" from three options.