While I cannot impart my entire knowledge of troubleshooting on you in this one post, I can still give you an insight into how I go about troubleshoot computer problems. I have broken the basics of computer troubleshooting into five steps, to give you an understanding of the process being used. This can be used as a basic guide that you can follow for anything problem a computer can throw at you.
Most professionals will tell you that five steps do not even come close to explaining the entire troubleshooting process, and they are (mostly) right. But I am not teaching you how to troubleshoot computers on a professional level, rather I am showing you how the troubleshooting process works so as you learn, you can develop your own troubleshooting method.
1. Identify The Problem
Now you might think that this is an obvious step but sometimes it is overlooked or not done properly. First off, you break the problem into one of two categories, either Hardware or Software. This is done by eliminating all possible causes of one section then the other or simply figuring out what an error message says. So an error message with a path to a program file is probably a software problem, while numerous beeps emitting from your computer during the POST is probably a hardware problem.
Note: if the error message gives you some sort of code, copy that down then Google it, or put it in a post on a forum asking for help.
Next you break it down further. If it is a software problem, identify the program and all possible causes that might be interfering with this program such as recently installed software, or other programs running at the same time that do the same thing as the program having (or creating) problems. If it is a hardware problem, attempt to isolate the issue by removing all peripherals one at a time and checking all of your hardware for any signs of damage, disconnected/frayed wires, or anything out of the ordinary.
2. Make A Plan
So you think you have identified the problem. You probably have, but remember, these problems might not be so straightforward as they seem. You want to create a plan on how you are going to fix it. For a simple computer problem, it can just be a little game plan in you head nothing fancy. Make a list of your possible causes and solutions to fix them. Then think ahead, and figure out what to do if those solutions fail. Or if other problems arise.
3. Prepare Your Arsenal
You have a list of probable causes and possible solutions, so now you need to gather the tools and programs you are going to use to fix this problem. If you do not do this often, you will probably have to go around downloading all the tools you need. Many people who do this often usually carry around a USB flash drive with various tools, programs and sometimes even a couple of operating systems. Some of my favorite tools are Hijack This, Defraggler, Ccleaner and Malwarebytes. I usually like to have a linux OS on my flash drive as well, either Backtrack or a rescue OS. Don't forget to include anti-virus software if there isn't one already on the computer. Remember, system utilities are still a vital part of any troubleshooting process.
Everything is now setup, you are ready to start the process of rescuing your computer. get to it! Remember: go slowly and make sure you are doing everything correctly.
So now that you have removed all the problems on your system, you should now make sure everything works correctly. Restart several times while checking to make sure anything and everything is working properly. Sometimes you might encounter a problem that you think you've fixed only to realized you broke something else in the process. Open all the programs you normally use, and keep your eyes open for any weird behavior or signs of another problem.