Windows 10 and Office 10 upgrade error on reboot OS not found

So my  wife has an ACER aspire v5-571. She successfully upgraded to Windows 10 and was working for a few weeks but then she tried to use office 10 and it told her she needed a key or she would have the 30 day free trial. Well she owns office so she says she followed the steps to get the key imported so she can use the office function cleanly. She rebooted her laptop and bam Operating System not found error came up.
I will tell you she doesn't login or use her laptop that often so when she does use it she usually has to get updates from McAfee and then reboot which happened this time as well.

Any idea why if she was successfully using windows 10 for a few weeks and then upgraded her office and her McAfee that all of a sudden her OS is gone?

I was thinking that maybe their is or was a latent worm that was set off with the upgrade to office 10 but it just puzzles me that only the upgrade would wipe it like that.

Also, the splash screen doesn't even show up for ACER. The second you power on then the Operating System not found error comes up.

Thanks and let me know if you need anymore.