need help with a pavilion g4 operating system recovery

[Mahi77422]

I replaced the hard drive on my pavilion g4 laptop. The new hard drive does not have a operating system. I have no access to the old hard drive. My question is am I able to restore the licence of old operating system, or do I have to order the recovery discs? OR do I have to buy the operating system all over again? And product key is visible on laptop. 

Thanks

[WAWood]

@Mahi77422 

With an OS that old, you're in a really bad situation now.

HP no longer carried recovery media for these devices and the other sites that used to carry it, do not either.  So, there is nothing you can order from HP or the other sites now.

There is the third-party site mentioned below, but it's all that I know of now and I don't know if it even still works:

You can try using Windows images downloaded using the tool from this site -- but there is no guarantee that this download, or the resulting ISO file, is going to work:

https://www.heidoc.net/joomla/technology-science/microsoft/67-microsoft-windows-iso-download-tool

Click the Download: Windows-ISo-Download.exe link. This will download that file to your PC. Double-click that file to run it.

Download the tool, run it, and do the following:
1) Select Windows 7 at the upper right
2) Under Select edition, select SP1 OEM -- this is the same as the HP OEM edition
3) Click the Confirm button
4) Select the product language, click confirm button
6) Select either the 64-bit or 32-bit download
7) Select a folder to save the file -- it's downloading 4GB or so of data, so that will take a while depending on the download speed. The progress bar might not show any progress but when the download is nearly done, a window will pop open indicating the ISO file is being moved from a temporary download directory to the folder you selected. The screen will then say Download Complete.

Once you have this, you have a choice of media to create:
1) If you can boot from CD, download and install ImgBurn and use the Write Image to Disk option to create a bootable DVD.
2) If you can boot from USB, download and install RUFUS and use the option to create a bootable USB stick from the ISO file.