It isnt hard to do yourself actually, and I would be more than happy to show you guides on how to do it.
What installing Windows takes is time more than anything.
First you backup any files that cant be replaced to an external drive. Documents, pictures, emails. Things like that. Dont worry about programs as programs can be reinstalled.
Then You get your hands on either a Windows 7 disk or a Windows 8.1, you boot off the disk and start the install. You delete all drive partitions to have one big one and tell Windows to install.
The rest of the install is automatic from there. When Windows is done installing it will ask you a few questions, like the user account name to make and a computer name. It will ask for the cd key during as well.
Once done and installed the first thing to do is to install the drivers. You can install the drivers before hand and save them on a drive. If it is a store bought computer you can grab all the drivers from the mfg site. Normally you need video, sound, network and chipset drivers.
Once the network drivers are installed you will be able to get on the internet, when you do you want to get all the Windows updates done first, this will take a while and will be large.
Once done though that part you start installing your programs and the move your files back over and your done.
Again time is what it needs most. But if you have never done it before it can be intimidating. But so was driving a car the first time, but after you do it, it becomes easier
While it is possible to fix the computer with a reinstall, some times it isn't when things are to far gone. Plus if you want to have the extra drive space then starting fresh is a good idea to avoid the nightmare of the 8 to 8.1 upgrade.
I fix a lot of systems, thus why I made my Windows repair tool. But sometimes there is no option but a reinstall when it would be faster than trying to fix it. Windows has over 1 million registry keys and trying to trace down a problem can be really hard. So my repairs are automated to help save the user time and a headache. But my program is always growing because as i find new things I add it to it.
So the first question is, what will be faster so you can get back to work? Trying to fix it or just wipe the sucker and start fresh?
Shane