Before you do ANY of that though, first of all list your specs, unless your laptop is considerably new, running Windows 10 will only make it run slower than if it were to run Windows 7 and also you might have driver incompatibility issues depending on what add-on hardware you use. Also, Windows 10 even after all this time STILL often has updates that break things, so there's that too... "Support" isn't always a good thing, 99% of the time the so-called "support" by Microsoft is stuff like new Internet Explorer versions and whatnot, totally useless stuff.
Anyways, to fix your laptop while keeping Windows 7, look into Windows 7's recovery mode, it should let you format to factory settings.