Troubleshoot Lettering

System Restore: It is recommended that if you have previously created a restore point, you can use the System Restore feature to restore to the previous state.
Restart your computer: Simply restarting your computer can sometimes solve the problem.
Change app language: Some users suggest that if the problem is caused by an app displaying another language, switching to the default English can fix the problem.
Check boot device: If messages such as “No boot device” or “Boot configuration error” appear, you may need to check the hard disk connection or BIOS settings to ensure that the drive is properly prioritized for booting.

Messages like "No Bootable Device" or "Boot Configuration Error" indicate that the operating system can't be found. Try checking your hard drive connections or looking into BIOS settings to ensure the correct drive is prioritized for booting.

It is causing by the app who is displayed in aother language. Switch to the default English to fix it.

Go to Advanced Options > System Restore and follow the prompts, this is a good idea.

Reboot your computer.

Which app you are using?

Is the problem solved?