Without reinstalling could try reset and click get started on Reset this PC
If nothing changes and would like to go forth reinstalling Win 10 it isn't hard, all pcs have usb. Actually it would be a good idea to have an usb stick all setup with Win10 handy in case you ever upgrade or change the hdd.
To setup an usb stick, best to get at least 8gb size usb stick for Win10 64bit.
Download Microsoft media creation tool when you have the usb stick handy, plug it in and then download and run the tool form
https://www.microsoft.com/en-au/software-download/windows10
Once you run media creation tool you'll be asked if you want to upgrade pc or create installation media, choose to create installation media.
Once you choose language Win10 etc, you'll be asked how you want to proceed, dvd or usb. Choose usb.
Media creation tool will download Windows 10 and set the usb so it can be used to boot with.
Once all that's done (can leave the usb connected to the computer) shut down the computer. I say shut down because bios splash screen is sometimes skipped if you click restart. Once you power up, look for the key to enter bios, usually delete.
Once in bios there should be an option called boot or similar indicating boot order for hdd, dvd or usb etc. Change priority to usb.
If you did that correctly the pc should boot on usb and start the process of installing Windows. If it continues to your old windows it didn't work.
[video="https://www.youtube.com/watch?v=SKbR6XT7fcA"][/video]