Basic Troubleshooting
Press and hold both the Power and Volume Up buttons for at least eight seconds to forestart your device.
If you phone don't respond plus in your phone and let it charge for up to 30 minutes, then try again.
If it still doesn't work, take your phone, proof of purchase, and warranty card to a nearby realme Authorized Customer Service Center for repairs.
Do this for better result
It is recommended to follow these steps to keep your phone in good condition:
*Periodically clear caches and go to Phone manager > Click on [One Touch Optimization] and reboot your device once a week.
*Uninstall APPs that are unnecessary or have bugs.
*Avoid multitasking too much at the same time. Click 'End All' to close apps running in the background.
Source: Realme