I do not see any screenshots saved on my machine
Look for a file named Dmanulla est.png in the default Downloads location for your browser... because that is what you are instructing WebDriver to do with the line:
driver.save_screenshot("D\amanulla\test.png")
Explanation:
The string "D\amanulla\test.png" will be interpreted as "Dmanulla est.png". This is because backslashes are escape sequences within Python strings. Your directory separators will be interpreted as \a (bell) and \t (tab).
Also, the : separator is missing between the drive letter and the file path, so it is treating the entire string as a filename. In the absence of a directory name, it should save to browser's default "Downloads" directory.
Solution:
driver.save_screenshot(r"D:\amanulla\test.png")
This uses a raw string so the backslashes are not interpreted as escape sequences, and it adds the missing : as the drive letter separator.