The GT720 is no loner supported in Windows 10 so I'm not sure if that may be an issue. Nvidia have the latest driver as a security update version 474.64 while newer card drivers are version 546.17.
The Control Panel should be available from the Windows 10 Store but mine stopped working some time ago. (I have a GT710)
Is your monitor a desktop monitor and if so can you select the setup buttons on the monitor and set it to a default.
I suppose it could be the graphics pushes 60Hz when the monitor cannot achieve it. Has this happened recently. Are you using HDMI or a normal video cable between the PC and monitor?