Download and install right version of ghostscript. In my case my PHP was x86 architecture, so I download Ghostscript 9.14 for Windows (32 bit).
Check, is imagick extension available and loaded.
This line should be present in your php.ini:
extension=php_imagick.dllAlso, check php_imagick.dll in PHP's ext directory.
<?php
	function genPdfThumbnail($source, $target)
	{
		//$source = realpath($source);
		$target = dirname($source).DIRECTORY_SEPARATOR.$target;
		$im     = new Imagick($source."[0]"); // 0-first page, 1-second page
		$im->setImageColorspace(255); // prevent image colors from inverting
		$im->setimageformat("jpeg");
		$im->thumbnailimage(160, 120); // width and height
		$im->writeimage($target);
		$im->clear();
		$im->destroy();
	}Call that function:
<?php
genPdfThumbnail('/uploads/my.pdf','my.jpg'); // generates /uploads/my.jpg