Hi Akashdeep,
The Dictate feature is only available to Microsoft 365 subscribers, Office 2019 that you are using now does not has this feature. Please refer to "Dictate your documents in Word", the below image is the screenshot of this article.
> for about 10 days there was dictate option but now it's not.
<< Have you ever install Microsoft 365 on your computer? Or was there a trial version of Microsoft 365 pre-installed before? The situation above may be caused by the residual information of Microsoft 365 on the computer.