My calling speaker is not working (speaker near front camera)

If the device hasn't been damaged by liquid, replacing the part is most likely the best course of action.

You can buy the part online for between 5 and 10 USD, and replacing it is relatively straightforward if you have the tools. If you don't have the tools, taking it to a repair shop is highly recommended.

In the event that you choose to DIY the repair, there are no iFixit guides for the A50 ear speaker replacement, but information from the other guides is still helpful. To put it simply, you'd need to remove the back cover and midframe. Then remove the motherboard and replace the speaker. The existing guides go into more detail.