Way is the speaker working

hi @rebiyatnuredin

Try using the headphone with the microphone attachment plugged into the phone when making a call or recording your voice or use the phone in "loudspeaker" mode (aka "hands free" mode) and check if you can be heard OK.

If you can this is just to prove that the voice transmission circuits in the phone are working OK.

Is the phone in a protective case?

If it is in a protective case, remove it from the case and check if you can be heard OK when on a call.

If it is not in a case (or even if it was and you still can't be heard) try using a vacuum cleaner to clear the voice inlet hole located on the bottom of the phone next to the earphone jack. Do not use a pin or probe to try and clear the hole as you may damage the microphone which is directly behind it.

If still no good the phone will have to be opened and the headphone/microphone flex cable connection checked and if it is OK perhaps the microphone has to be replaced.

Here's a video that shows how to remove/replace the headphone/microphone flex cable (supplier example only).

At 3:58 minutes into the video the headphone flex cable is being removed and as can be seen at 4:14 minutes the microphone has broken off the flex cable.

If doing all this yourself seems to daunting, contact a reputable, professional mobile phone repair service and ask for a quote to fix the phone.