There are many programs that are considered popular among PC/Mac/Linux users. For instance Firefox as a web browser, Handbrake as video conversion software, VLC as the video player that doesn't quit. Software like this is awesome, but it is only awesome when everything is working fine.

What I'm looking for is software that you use when there is some kind of a problem with your machine. Software that gets you out of that sticky situation that you're unsure if you're even going to be able to get out of. I'm talking about file recovery, password recovery, analysis software, Live CDs, etc...

I'm sure there are tons of programs like these that I don't know about and I would like to add them to my arsenal. I will choose the best answer based on the most helpful suggestion that I have not heard of yet. The software can be for a specific operating system (or even file system), or it can be for more than one.

I'll start off with some examples of software I use in emergency situation that some of you might not have heard about.

File Recovery/Disk Management

Recuva (Windows only) - This program has saved me on more than one occasion. It is free and supports multiple modes of analysis. It has a quick mode that recovers files that have merely been deleted using the trash can. It also has a deep scan mode that can recover files after a format. I have seen this program do amazing things in the past and it has worked better than any other paid solution I have found.

Spinrite (OS Independent) - Spinrite runs off of a boot disc (that it creates under windows). The boot disc can be ran independent of the OS you are using as it runs it's own. I can't possibly cover everything that it does (so check out the author's website), but it is a great piece of software. It will go through your drive and correct any errors that exist. It will recover bad sectors if it decides that they were marked bad mistakingly. It tries very hard to recover any lost data. It will attack the sector by spinning up from various directions just to be able to figure out if that bit is really a 1 or a 0. If you find yourself in a situation where your computer won't boot and you think the hard drive just died along with all your precious data you owe it to yourself to give Spinrite a go.

General Recovery Tip

Some of us know this and use it all the time, others do not. If you are unable to boot into windows and you have tried everything possible, it does not mean your data is gone. Download one of the many Linux Live CDs and boot from it. You will be able to mount your Windows drive and get access to your files (as long as the hard drive is not completely dead). You can then copy those files from the faulty drive to another one.

What emergency software do you use?