Assuming the cable to monitor is not burning out, then the next thing to check would be Resolution settings ( which may have been changed during an update [ especially, if the Display drivers were changed ] ).
- Click Start > Settings cog > System
- On left pane select Display
Here you can verify whether the screen resolution has been changed, and if necessary adjust it to your preferences
You can check
Device Manager to see whether the drivers have changed or whether attention is needed ( usually indicated by a yellow icon with an exclamation mark ).
- Type Device Manager into the Cortana search field, then press Enter key to open
- Expand Display adapters and confirm it is correct. If not update it, by right-clicking on the adapter listed &selecting Update drivers
- Likewise, expand Monitors and confirm the correct model is listed. If necessary change that.
Other than that, on the Monitor itself, there ought to be a Menu button. You ought to be able to press this and select an option to
reset to default settings, which should set the monitors resolution to the Manufacturers recommended settings.
Regards,
Regedit32