Okay, so your computer is misbehaving and you don't know what's the matter with it. You have come to the right place. This site is all about diagnosing the common problems that computers develop. It is easy, and the diagnosis costs nothing.
Here is how simple it really is. If the computer is performing poorly or doing weird things the problem most likely is caused by one or more of these three things:
There are a number of high quality computer programs available from large, reputable companies that address each of these problems. The programs selected here are all high quality commercial software, but the great thing is they will diagnose your computer system completely free of charge. They will perform an analysis of the computer system and present a comprehensive report of the problems found. They will also offer to fix the problem for you for a fee, or you can fix the problems yourself. You can decide what to do once you have the diagnostic reports.
At the highest level, there are three major phases to the
process of restoring full happiness with your PC. These
are:
First and most important, have any important files been deleted or overwritten? Important files such as proposals, reports, manuscripts, irreplaceable pictures and such, for which there are no copies or backups? If there are, then recovering these is the first priority. Do not keep surfing the net, as the longer you leave it the less likely the file will be recoverable. See detailed instructions to recover deleted files. Once you have recovered all that can be recovered, return here and continue the procedure.
After the recovery of lost or deleted files, the next step is the preservation of your important files that aren't lost. Copy your important files to a safe place that can be detached from your computer just in case something goes very wrong. You can
Once you have ensured that your valuable data is safe you can be more at ease through the next steps.
The complete diagnosis consists of several parts and all parts should be run, though the best sequence to run them is dependent on what the worst symptoms are. In most cases, doing the steps in the sequence shown in this flowchart will work fine. The three boxes in the image below are clickable, or use the links under it.

The Steps for Diagnosing and Repairing a Computer System
Run the diagnostic software for each step in the flowchart and fix what is found before moving on. It would be incorrect to run all diagnosis steps first and then try repair them all at once. Click on the flowchart or use the navigation bar at the top to reach the page that addresses that step in detail.
Now that your system is clean let's make sure it stays that way. Rescanning it periodically for spyware and viruses is not as good as keeping them out in the first place. A top-quality anti-virus software costs only a few cents per day to use - isn't that well worth it to avoid all this hassle in the future? We recommend a few excellent anti-virus programs here.
And while we're talking about safeguarding, let's mention backups. Everybody knows they should be backing up their systems regularly, but a high percentage don't do it, because it's extra work. In the early days of PCs, making backups meant sitting and swapping floppy disks in and out of the computer for hours. Today it is a lot less painful. The backup programs that we feature here are set-it-and-forget-it backup solutions. They perform unattended backups of all your important files to the destination of your choice, which can be another hard drive on your PC, a different PC on your local network, or to a backup site over the Internet.