Hi Charazel, can you please let us know the model of your device?
As advised by RedDogRabbit, you can try Booting into Recovery by Wiping Cache partition. If you wipe your cache partition, it removes any temporary files that may be causing some problems or issues with your device, all of your personal files and/or settings will not be affected when you wipe cache partition.
1. Hold the Power button and Volume Down to open the power options where choose the Power off.
2. When the screen goes dark press the Volume Up and Power keys together.
3. Let go of all held buttons when you see the Recovery mode on the screen.
4. Then you should select Wipe cache partition. Use Volume Up to navigate and the Power button to accept it.
5. Choose Yes and press the Power key to confirm that operation.
6. After that select Reboot system now with the Power key."
To uninstall WhatsApp go to your device's Settings. Tap Apps & notifications > WhatsApp > Uninstall to remove the app and all of its data.
If nothing works, then please perform back up and factory data reset on your device.
