Hi there,
If you didn't uninstall Wise Reminder and download, and install it again, you can do as the following instructions and screenshots below to get your reminders back.
1. Download and install Wise Reminder first
2. Press "Win"+ "R"
3. Input %appdata% in the box ---click "OK"
4. Find out the folder named "Wise Reminder"
5. Find out a file named "ws_rmind_data.dat",
6. Run Wise Reminder---Restore---Restore the file named "ws_rmind_data.dat"