HDD won't show up in Mac Finder. How to recover data?

[Alexacy]

I have a 500 GB Seagate SATA hard drive formatted as the default "Mac OS Extended Journaled" in a 2008 MacBook Pro Mac OS X 10.6.8 v1.1. HD partitioned 1/2 Time Machine, 1/2 important data. Everything worked fine until I was plugged it into my new TV and now I can't see the data part on my laptop anymore...only the time machine part shows up on the desktop. Now when I boot the computer, I get a flashing question mark over a gray folder (This means that no bootable OS was found). The hard drive won't show up in Finder, therefore, any disk repair/recovery utility I try can't find the hard drive to repair it.

I need to recover some important files from the hard drive.
Any hints, suggestions, and/or answers would be greatly appreciated.

[Doomer]

There are plenty of recovery utilities on the market
For Mac I can recommend Data Rescue, for Windows - R-Studio
You need to make sure that you drive is in good conditions first. You need to get SMART and post it here

[bcometa]

The hard drive won't show up in Finder, therefore, any disk repair/recovery utility I try can't find the hard drive to repair it.

If may still show up in Disk Utility, does it? If so, it's possible you could get it back up by "Repair Disk." But, as always, best to clone the drive first before doing anything, or it may get much worse. If it doesn't show up in Disk Utility, there is nothing else to try (at least as far as software recovery is concerned).

**Before trying to Repair if it shows up in DU, you may want to try DiskWarrior. With DW, you can create a "preview" version of the "repaired" drive to make sure it's fixed correctly before going through with the "repair." Hint: you can also move data directly from the "preview" partition DW creates, instead of writing the repaired catalog file to the drive, which may cause more problems if the drive has physical or mechanical problems.

***FYI… R-studio has a Mac version also (UI is clunky, but it works).

[harddriverecovery]

Before investing a big amount of money in a data recovery software program, you may want to be sure that the drive is actually working. Make sure that it is not making any clicking or buzzing sounds first, and also checked the disc to see if it is spinning. From there, you'll want to take a look at software programs.

[poehere]

I agree about first diagnosing this drive and can you even see it? Does it spin up? Does it click? This is your first step in this one. Next step is to find out why it is no longer visable to you and you can not see it anymore.

If it is a Seagate it could have other problems. But need more info on this one.

Then if you finally get it fixed then there is cloning and recovering data after this one.

If you can not do this one take it to a DR company in your area to diagnose the problem on it and give you a price to fix it. You do not have to accept repair on this one but you will have a better idea of what is wrong with it and know more about your problem.