Plug in the USB flashdrive, start the laptop and get into BIOS (press F2)
When in BIOS check that under the Main tab, that Fast Boot is disabled. (When fast boot is enabled the USB ports aren't checked on startup).
Also check under the Boot tab that Secure Boot is disabled.
You should see the USB flashdrive listed as a boot option.
Save the changes and exit BIOS and restart the laptop.
When the laptop restarts press F12 and then select the USB drive as the desired boot device.
I doesn't help if you don't answer whether or not you've checked what I suggested above. If it still doesn't work then at least there are other things to try but unless you tell us we won't know!
Create a Win 10 recovery disc, either by downloading online or from any known working Win 10 PC.
In the host PC go to Control Panel > Recovery > Create a recovery disc and follow the prompts.
Doing either will create a bootable disc that you can install Win 10 from.