Before reinstalling windows try an sfc scan in command

https://support.microsoft.com/en-ca/help...

If this brings no joy then try reinstalling windows but before you wipe the old hard drive you may also want to recover your oem key if its not on the back of the laptop . without the key you will need to buy a licence for a new OS to recover the key you can pull the hard drive and connect it via sata cable to another computer and use a program likemajic jellybean I use this all the time to recover oem keys . This is another thing to try

https://www.youtube.com/watch?v=TF4B1kuh...

after trying all of these let use know and we can go from there

Hope this helps