as an electrician I'd say you could probably solder it back together just make sure you use electrical tape to separate and insulate the wires so they don't short out if its a ribbon cable you're probably in trouble and it would be necessary to buy a replacement one. Best of luck, -Brad
I'd say everything would take you about 10 hours as far as installing windows id give windows 10 another shot id download the windows 10 boot drive installer you can get free here https://www.microsoft.com/en-us/software-download/windows10 and you'd have to go in the bios settings of your computer to install it its different for every computer so you'd probably have to go into your user manual. Installing the ram will take a matter of minutes just make sure you buy ram that's compatible with your computer. as far as changing the case goes you'd have to go at your own pace but that would probably take me about 4-5 hours.