Src is not recognized within image element

i have got some issues that within img element the url is not recognized so the image doesn’t appear i have tried some others links that i copied from google but still and in fact there is once that works i brought it from the course of basic html and i wanna know why and where is the problem

<img id="image" src="" alt="sherlock holmes" >

If you are copying from Google, make sure it is Copy Image Location

you don’t provide any code to see so its hard to fix it but…
if you have it in the same file with the html

<img src="imagefileName.extension">

if it is in a different folder

<img src="/folderName/imagefileName.extension">

if it is from a url

<img src="">

thanks a lot it is really helpful