You don't need your Windows 10 product key and you don't need a third party app to retrieve it. It will be automatically retrieved from the UEFI when you install Windows.
You can either install the free vanilla variety of Windows 10 from Microsoft's website, or purchase your original Acer OEM Windows 10 recovery media from Acer store. Again, you won't need to enter a Windows product key in either case.
https://www.microsoft.com/en-us/software-download/windows10
http://us-store.acer.com/erecovery/rcd
If for some reason you had installed Linux in legacy mode, the link below explains how to get back to default UEFI mode. The link is about Windows 8.1 but it's the same instructions for Windows 10.
After your computer is stable, make sure you have the latest BIOS.
