Hi, good day! I'm John Dev a Windows user like you and I'll be happy to assist you today. I know this has been difficult for you, Rest assured, I'm going to do my best to help you.
When was the last time it worked properly?
Please try to reinstall Notepad
Press Start then search Optional features
Find Notepad in the list then click Remove
Restart your computer
After that, Press Start then search Optional features again
In the Add an optional feature, click View features
Select Notepad in the list then Install
Please try to open .txt files with Notepad
Right click the .txt file then select Properties
Click Change then select Notepad
Click Set default
Kindly let me know if this helps or if you have any further concerns by clicking the "Reply" button at the end of my response. I will appreciate it.
Kind regards,
John DeV
Independent Advisor