Memory cards are automatically recognized by the Huawei smartphone and released for use. If the memory card was unmounted, however, it must be made available again.

Android 10 | EMUI 10.0
Step 1:  Open the  settings
Step 2:  Tap on  Storage
Step 3:  Tap on  Memory card
Step 4:  Tap on  Mount
  1. Open the settings
  2. Tap on Storage
  3. Tap on Memory card
  4. Tap on Mount

Huawei Instructions