Is it a laptop or a desktop?
If you have a back up copy of windows somewhere, or a Windows 7 install disc, you might be able to reverse it, but if not, you're probably stuck with 10 unless you want to buy an install disc.
Microsoft has done away with the IE browser from 7 for their new "Edge" browser that comes with 10.
You can set the homepage on any browser to whatever you want. In Edge, if you look in the upper right hand corner, there's a symbol with 3 dots. Click it. Then look for the word "Settings", and click that. When that menu opens, there should be a section with four options beneath the words "Open with". The last of the four options should be "A specific page or pages". Select that and click on the drop-down box and select "Custom". A new input box should have just popped up and you can input the web address into this box and hit enter, and it will save that as a page to open up to.
You can choose between their "Light" and "Dark" theme, but I'm not familiar with Edge beyond that so I don't know that you'll be able to get the old "feel" of IE back.