how do I access deleted information?

Recover Files in The Trash

If you simply put files in the Trash you can restore them by opening the Trash (left-click on the Trash icon) and drag the files from the Trash to your Desktop or other desired location. OS X also provides a short-cut to undo the last item moved to the Trash -press COMMAND-Z.

If you empty the Trash the files are gone. If a program does an immediate delete rather than moving files to the Trash, then the files are gone. Recovery is possible but you must not allow any additional writes to the hard drive - shut it down. When files are deleted only the directory entries, not the files themselves, is modified. The space occupied by the files has been returned to the system as available for storage, but the files are still on the drive. Writing to the drive will then eventually overwrite the space once occupied by the deleted files in which case the files are lost permanently. Also if you save a file over an existing file of the same name, then the old file is overwritten and cannot be recovered.

General File Recovery

If you stop using the drive it's possible to recover deleted files that have not been overwritten by using recovery software such as MAC Data Recovery, Data Rescue II, File Salvage or TechTool Pro. Each of the preceding come on bootable CDs to enable usage without risk of writing more data to the hard drive. Two free alternatives are Disk Drill and TestDisk. Look for them and demos at MacUpdate or CNET Downloads. Recovery software usually provide trial versions that enable you to determine if the software would help before actually paying for it. Beyond this or if the drive has completely failed, then you would need to send the drive to a recovery service which is very expensive.

The longer the hard drive remains in use and data are written to it, the greater the risk your deleted files will be overwritten.

Also visit The XLab FAQs and read the FAQ on Data Recovery.

If you did not empty the Trash, click on the Trash icon at the right side of the Dock and drag those files to a different location.

If you emptied the Trash, it is more difficult. Typically, when a file is erase, it is not really erased. The space the file occupied become unallocated, so that new data can be written over that space. If new data files have not yet been written over that space, the old data is still there and may be recoverable.

There are utilities specifically for data recovery. For example (I have not used)

http://www.filerepairtools.com/mac-data-recovery.html

Other more general utilities, such as TechTool Pro by Micromat, have a data recovery "module" as part of the package. I have this utility (and it's a good product), but I have never used it for doing data recovery.

You may be able to use such tools to recover erased data. If you intend to try, you should use the disk that held the erased data as little as possible, to reduce the likelihood that new data files will be written over the space used by the old data.

Mac Data Recovery is a best utility that restores the corrupted, damaged, deleted or formatted data from HFS, HFS+ file systems of Mac hard disks. Comparison and read the reviews here http://www.comparisonandreviews.org/mac-data-recovery.html