Ok, go to start screen, then type in restore point, then click on the settings. There you will get an option to create a restore point. From there it will guide you through when you want to restore it from etc Hope it works!
You have to be careful nowadays. I nearly clicked on a "Flash update" message the other day when surfing the Internet. Then upon looking closer I realised it wasn't a legit site at all and was an advert looking to trick me into installing their program. No doubt full of crapware.
I suspect it's what you did. It's worrying really. I'm a techy IT geek who is paid to be on top of these things yet nearly fell for it myself. So I wonder how many normal people have been tricked into it.
Glad you sorted it out to the point that you can do stuff, but you need to be really careful: your computer may well still be infected. Most likely explanation is that you downloaded a virus or other malware. You can't rely on being able to uninstall viruses from the control panel.
Never, ever agree to install something that you haven't deliberately selected, especially from a popup. It's very unlikely that what you downloaded was flash player, and if it was a virus it won't call itself 'flash player' to allow you to uninstall it.
You should run additional diagnostics (e.g. spybot search & destroy) to ensure that your computer is clear from malware: just because the popups are gone doesn't mean it's all OK now!
Using Windows 8 is U in its own right. I've also had various experiences of computers going Pete Tong when Flash stuff gets installed. Really downloadable stuff shouldn't be changing local config or writing to drives without explicit user permission. It's not surprising that the makers of other OSs won't support Flash because they consider it insecure.