Hello Lanna, welcome to the Microsoft community, I'll be happy to help you today;
I understand that you are having issues with reading PDF in Edge;
Initially I recommend that you check if you are updated with the latest version of Windows 10;
Press Windows key + i and go to Update and Security;
Click Check for updates and do ALL pending updates;
Check for updates to Edge;
Open Edge and go to Settings;
Click on About Microsoft Edge in the menu on the left of the screen;
If there is an update, it will be done;
Try repairing Edge;
Press Windows key + i and go to Applications;
Select Microsoft Edge from the list and click Modify;
Click Repair;
Wait for the process to finish and try to open PDF files again;
Hope this helps, see you soon!