In Recovery Mode, the touchscreen usually doesn't work. Use the Volume Up/Down keys to move and Power to select.
If the phone stays on the Huawei logo for more than 10 minutes after a reset, try the hardware key method again. huawei l21 hard reset
This method is best if you cannot access your phone's settings menu because it is frozen or locked. Turn off your Huawei L21 completely. In Recovery Mode, the touchscreen usually doesn't work