There are a few things you can do to try to fix a flickering screen in Windows 10:

1. Restart your computer. This can often fix minor software glitches that can cause screen flickering.
2. Update your display drivers. Outdated display drivers can sometimes cause screen flickering. To update your display drivers, go to the website of your computer manufacturer or graphics card manufacturer and download the latest drivers for your device.
3. Change your refresh rate. A higher refresh rate can sometimes reduce or eliminate screen flickering. To change your refresh rate, right-click on the desktop and select Display Settings. Under Related settings, click Advanced display settings. Scroll down to Display adapter properties and click Adapter properties. Click the Monitor tab and select the desired refresh rate from the Refresh rate drop-down menu. Click OK to save your changes.
4. Disable Aero. Aero is a Windows 10 feature that can sometimes cause screen flickering. To disable Aero, right-click on the desktop and select Personalize. Click Themes and then click Theme settings. Under Advanced theme settings, click Aero. In the Aero dialog box, select the Disable Aero checkbox and click OK.
5. Run a virus scan. A virus or other malware infection can sometimes cause screen flickering. To run a virus scan, open the Start menu and type Windows Defender. Select Windows Defender Security Center and then click Virus & threat protection. Click Scan options and then select Full scan. Click Scan now to start the scan.

If you have tried all of the above and your screen is still flickering, you may need to replace your monitor or graphics card.