If I don't on loud speaker in call , opponents don't listen my talk

Correct me if I'm wrong, Hasanul, but it seems to me that you're saying when you're on a phone call that the other person can't hear you unless you put it on speakerphone. Is that correct?

If that's the case, it sounds as though the lower microphone that's used during phone calls has failed. When you change to speakerphone mode, the phone switches to the upper microphone, which is still working , apparently. Check the speaker grille and make sure it isn't clogged up or blocked, but if that doesn't help you may have to replace the microphone.

On your phone the microphone you're concerned with is mounted on the lower auxiliary board along with the charging port, so replacing that board will give you a new microphone.

I was unable to find a guide specifically made for your A50S, but at least one YouTube video I saw claims the procedure they show works on both the A50 and A50S.

Samsung Galaxy A50 Charging & Headphone Port Board Replacement

Of course, if that's true, then you could simply use the step by step iFixit-style guide on the Spanish site Nadie Me Llama Gallina.

Manuales / Samsung Galaxy A50 / Auxiliary plate

The port itself is available on a wide variety of sites; I usually start by checking Amazon, eBay and AliExpress. Here's one of the first ones that came up as an example.

For Samsung A50S USB Charging Port Board Charger Dock Microphone Mic A507 A507F A507FN Original Phone Repair Part Replacement - AliExpress