Big problem after windows 10 upgrade.

All was well in my digital world before windows 10, I thought it was the future for me but sadly it isn't the case, after a few weeks of use, the wireless adapter in my desktop stopped working on 10, it didn't cease to function, it disappeared without a trace from the device manager and no matter how i reinstalled software or restarted I could not get it back, until I was forced to install windows 7 again, which solved the issue.

Now I have reached a similar impasse with my laptop, an MSI stealth pro 2pe, which had a recovery function built in, I hoped in vain that the function had windows 8.1 still tied to it and it would fix the issue, but when I attempted to recover it only gave windows 10 as an option, I then made a media tool for windows 8.1 and that has installed, but the WiFi adapter is still missing, when I try to install windows 7 on the laptop, the setup fails (via the USB key while actually on windows) and when I try to install it by boot order in the bios it just skips straight to login for windows 8.1.

What can I do to save this computer from this terrible affliction, it seems to plague me wherever I go, I am worried that my wife's new lenovo laptop will have a similar issue and not be able to recover also.

Are you still having these problems? From what I can tell of your problem, you were able to restore via ISO to Windows 8.1 correct? But you still couldn't get on the internet. Without knowing your wife's computer version I can't help with her Lenovo, however one of these should fix your wireless connection problem for windows. If you have Killer Wireless, download from here. Otherwise download here. These should fix your internet connection on windows 8.1