If you have a valid readable COA sticker on the laptop you do not need to buy a new Windows disc.
If you are trying to use the OEM Recovery option to restore the PC you need to use the keyboard arrow keys to select the option and then click Enter.
You can't use the mouse to click on this (if that's what you are trying to do).
This tutorial has instructions for everything needed to re-install Windows including how to download the ISO and create a bootable installation Disc or USB Flash drive. Clean Reinstall - Factory OEM Windows 7
If you can use the factory recovery option that should be easier for you to restore the PC to Factory condition.
If you are willing to do a Clean re-install you will have a better running PC.
If you can't create a bootable installation disc or flash drive on your laptop, create the media on another PC.