From time to time, we seem to get a lot of questions from individuals who have saved some file to a drive or other removable media, and later are unable to open it. Some are frantic because the file contains critical data for a project they are working on, while others just want to know what happened and how to prevent it.

Retrieving data from files that can no longer be opened by the program that created them is usually pretty difficult, if not impossible. It's hard to give much meaningful general advice because the approach and options will vary quite a bit depending upon the nature of the file. Text files can be easy to get open, while database files or MIDI sequence files are usually impossible. A few things you can try are:

• Copy the file to another drive and see if you can open it from there (not likely)
• Run a file recovery and repair utility such as Norton Utilities
• On the Mac, you can get a utility such as ResEdit that will allow you to go in to the file and change the file type and creator, which can sometimes remedy the problem

In rare cases, you can contact the maker of the program that created it and see if they'll let you send them the file to look at. Quite often, if you can get this far, they can get the file open and resave it for you.

There are a few steps you can take to prevent the problems from happening, assuming this is a rare occurrence for you (meaning your system is basically functioning correctly). Most of it is common sense like using high quality media, keeping your drive tuned up with appropriate utility software, formatting with the recommended software and having the correct drivers installed, stable power, and not exposing your system or media to hostile environments. Hostile environments can include things like excessive heat, sunlight, and strong magnetic fields (motors, TV sets, and lots of other things can reek havoc on your system just from the fields they emit). Low quality media and unstable power are something we see pretty frequently causing computer users problems.

It is always possible for things to randomly go wrong at any time and these events (static discharge, power spikes, etc.) may occasionally take out a particular file or disk. I like to say, "It must be sun spots." Not like it's literally the result of sun spots; that's just a way of expressing that random events can occur (although we are in an unusually high period of sunspot activity right now [and it does seem like these problems come to us in cycles.... hmm]). Anyway, this type of random failure is rare enough that we don't normally worry about it.

One of the best ways to prevent problems falls in the "hindsight is 20/20" category. BACK UP YOUR DATA. There are 20 great reasons to do it; this is only one of them. A good percentage of the time a file like this is bad from the moment it is written, but there are certainly plenty of instances where files become corrupt after they've been on the media for a while (not to mention the chance of the entire media becoming unreadable). If you have a backup history you can go all the way back to when the file was initially written and see if you can recover it. Even if you don't have a real backup strategy in place it is still wise to copy critical data to more than one location. And if the data is critical it's a good precaution to open the file right after you save it, just to make sure it saved properly. If you use a combination of all these techniques you should almost never get stuck without your data.