What could be the problem?

After successfully running the app the first day it worked…today i tried but all i can see is this…Kindly help

Check that you have uploaded the API properly and that the correct API link was added to the frontend before compiling. If no changes were made to the project after it was working, then changes might have been made on the server. Contact your hosting provider to find out what changes were made, if any, and then you can determine what caused the issue with your app.