Loud clicks from a computer that won't boot. The blue screen of death, followed by an invitation to reformat a drive already full of treasured files. On a Mac, a folder labeled with an ominous question mark. Any could be a sign of that dreaded digital disaster: a hard-drive failure.

So who ya gonna call? Don Anderson hopes you'll consider his Gloucester City company, Tri-State Data Recovery & Forensics L.L.C.

Anderson says he has the Philadelphia region's only Class 10 "clean room" for data recovery, and it's hard to find evidence to the contrary. Competitors pitch "Philadelphia" services from as far away as Florida and California, listing local addresses that are UPS sites or, as one Virginia company describes it, a "virtual receiving office."

I can't vouch personally for his services, though some satisfied customers have done so online. Tri-State also does business as SouthJerseyData.com and PhiladelphiaDriveRecovery.com.

But Anderson, in business in Millville for the last three years, recently moved his one-man shop to a site near the Walt Whitman Bridge, so I stopped by to see how the process works.

Wherever you find it, data recovery isn't cheap, though low overhead plainly helps Tri-State beat the competition.

For instance, TTR Data Recovery Inc. of Fairfax, Va., charges about $1,300 to $1,700 for recovery after a head failure - a common hard-drive catastrophe. Wired magazine's Mat Honan reported paying $1,690 last year to California-based DriveSavers, one of the big players in this niche. Anderson says he charges $800 plus parts for similar work.

Who needs data recovery? If you routinely back up your hard drive, chances are that you'll never need to pony up. But Anderson typically takes in about 10 drives a week, both locally and from as far away as France and Albania. Plenty of people ignore the backup scolds.

"Most of my customers are businesses," he says. "About 30 percent are people that just want the photos of their kids back. Pictures are very sentimental."

An Elkton, Md., businesswoman offered a typical case. She punched her laptop - something we've all been tempted to do, no doubt - and it paid back with a disk failure. The diagnosis: damage to the disk heads, small components that older customers might find reminiscent of the arm on a record player.

But rather than reading analog data from an LP spinning 33 times a minute, a drive head reads magnetic data from glass or aluminum platters that rotate thousands of times per minute. If the head gets even a little out of whack, it can mar a disk and render some sectors of the drive unreadable.

Some of the simplest kinds of recoveries, such as capturing data from a drive infected with a virus, can be done inexpensively with recovery software, perhaps at your neighborhood computer store or even at home.

But be warned. Anderson says it's a big mistake to run such programs on a drive after a mechanical failure, because a damaged head will keep on scratching the surface. "They beat it to death with software," he says.

Other mistakes? Following bad home remedies from the Internet, such as putting a broken drive in the freezer or oven. Really, people do that, he says.

Anderson, 33, learned his craft through training from a Georgia company, My Hard Drive Died, and from on-the-job exposure as a contract IT worker. He's invested about $60,000 in tools designed for special aspects of the work, such as examining hard drives with a microscope. A DeepSpar Disk Imager, made in Canada, helps read bad disk sectors. A $7,000 Russian device helps repair crucial computer firmware. Other tools help him repair old Windows XP drives, or multidisk RAID arrays used by businesses.

Anderson charges $50 for diagnosis, but after that customers pay only if he recovers data.

The Maryland woman? She got her QuickBooks files back. "The other stuff she didn't really care about," he says.

215-854-2776 @jeffgelles