Any Freeware to Undelete Items Emptied from Mac Trash?

I received a question from a student, asking me this Mac related recovery question:

I just emptied the Trash bin on my MacBook and later found I just made a big mistake as I have deleted an important folder (full of desperately needed documents & pics). From the net I know that as long as those files are not "secure deleted", chances of recovery are there. But I have spent a lot of time working on it by trying several Mac undelete software, none of free trial versions allow me actually recover my folder & files unless I register the application (which means I have to pay for it). Please help me out and give me some freeware for undeleting trashed mac files. PLEASE tell me I am still a student. I'm desperate for help.

[update on June 20, 2016: if your MacBook is with a solid state drive (SSD) instead of a hard disk drive, things can be quite different. Simply put, when you erase a file from SSD-based Mac, it’s beyond recovery. This is due to how the “Trim command” organizes a file in a SSD. Thanks to Lorena for pointing out this. Read her macbook tip here.]

Well, unless the Mac disk has been completely destroyed or broken, there is a chance to retrieve the files. So, my first advice would be try your best to protect your Mac machine from any physical damage.

And then the next step to recovering your data is to stop using the drive containing the lost files. Mac OS X overwrites free space very quickly with temp files. If your missing files are on your boot drive you will want to shut down your Mac right away.

Freeware to Undelete Trashed Files on Mac

If your Mac is running OS X Snow Leopard or above (including latest Yosemite, El Capitan), you can rely on this powerful backup tool - Time Machine, which is equipped with Mac machine that can backup almost anything and everything on a Mac timely. Once you deleted or lost some files, just enter your Time Machine browser, you'll easily restore your trashed Mac Items. This video shows how:

If you haven't set Time Machine or it just fails to retrieve your data, then I suppose the only way is to use a third-party Mac data recovery tool, see this list of totally free Mac data recovery software.

In fact, when a file is deleted off your Macintosh hard drive or partition, it's only the address of the file that is deleted from the files table. It's like having a huge book that has come unbound and lost its table of contents. The pages are there, but without the table of contents, it's much harder to find a specific chapter. Mac undelete software rebinds the book and scours the deepest parts of the hard drive that you can't access.

How to Recover Data from External Hard Drive Not Recognized by PC

Whether you are using a PC or a Mac, having a handy external hard drive (such as Western Digital Essential 500GB, Seagate FreeAgent 1TB etc) is definitely necessary when it comes to backing up important data just in case.

[Update July 12, 2016: I now use Google Drive for additional backup. You can also use other online backup services. Price of such services have been dropping. In my opinion, due to constant risk of using hardware for backup purposes, it's best to turn to cloud storage]

But the question is what if your external drive cannot be recognized or detected by your computer? How do you recover data from an external HDD not even recognized? These problems do happen here or there.

Today I'm going to show you how to fix two common issues related to data loss from an external HDD.

If Your External Drive Can be Detected by a Computer, but It Shows Errors...

In this case, your drive should be found via "Disk Management" or "My Computer" (or "This PC" if you are under Windows 10) when it is connected to a PC. But typical symptom is when you attempt to access the drive, it pops out some error messages such as “the drive is not formatted”, "The drive cannot be accessed", "RAW drive is not initialized" etc. The cause for this can be the drive is corrupted, faulty due to improper usage, or simply because the disk has been used for too many times (every technology has its own lifespan(.

Here're some general fixes:

• Step 1: See if you can use Recuva (or Pandora Recovery) to retrieve some data. Connect your external hard drive to a PC first, then download and install the recovery program to start a quick scan (no luck? go Deep Scan after that).
• Step 2: Once you retrieve your data, try formatting the faulty external using Windows internal format option. Go to Disk Management and select your drive and click "Quick Format" function.
• Step 3: Now your drive should work normally again. Note: if you have important data, you can re-use the data recovery software to scan your device again. Because a quick format won't erase the data immediately. Learn more from this external drive formatted recovery guide as it explains how.

If Your External Drive Cannot be Recognized or Detected…

There are many possible causes for this issue, for example, outdated Windows driver, bad sectors, faulty USB cable, physical damage etc.

Try these steps to see if you can fix it.

• Step 1: Re-connect your external drive to the PC via another USB cable (to eliminate faulty issues). If it doesn't work, go to next.
• Step 2: Check if there are some drivers missing or you forget to install on your PC. The best way is to go to the official website of your external drive provider and download the latest drivers. Western Digital here, Seagate here.
• Step 3: If there is no problem with the driver, then most likely your external drive has suffered physical damage or severe bad sector errors etc. I highly recommend you contact your device manufacturer for services.