Yasuo.. the easiest way to fix these things is to keep daily /weekly / or monthly backup images of your primary partitions..
Windowz 7 can create full backup images.. thereby, when there is a problem, it does a COMPLETE restore to a prior state.. without any fiddling..
I've come to accept that this is by far the MOST time efficient way to deal with computers as a client user..
The time it takes for you to find out what the problem is, fix it, prevent it from happening again, etc is about 10x the amount of time it would take to restore from a portable SSD.. only about 15 minutes..
Personally, I keep 30 days of back up images, that's only 6TBs.. I can restore to any of those states..
My point is... EVEN TODAY it's not worth it to FIX the problem you have now.. Just back up your documents, and reformat.. and start creating restore images on external SSD or HDD..