Hi Ribha,
Ribha
<iframe src="@row.BookLink" style="width:645px; height:700px;"></iframe>
What's the value of the row.BookLink? You could get the value in the code behind, then check out it. If it is relative path, you could set the src attribute of iframe as hard code, for example:
<div class="pdfifram"><iframe src="/Books/pdf1.pdf" style="width:645px; height:700px;"></iframe></div>
If it doesn't work, the src path should be incorrect. You need to find the right path.
If it works well, I suggest you using developer tools(press F12) to inspect the element.
Best Regards,
Candice Zhou