Looking for way to recover my data in a corrupted External HDD

[bless4decency]

I was trying to access my external hard disk and the computer responded that the hard disk is corrupt and unreadable and when i tried the chkdsk command, it said the type of file system, chkdsk is not available for RAW drives. what do i do? i have some very important documents that i wouldn't want to lose. Please i desperately need help.
thanks

 

[DR_Luke]

If your data is of value to you, you should seek professional data recovery assistance before too much damage is caused. There is a post about partition showing as RAW which helps you better understand what could be going on.

Should you want to seek professional assistance, a few labs with reasonable prices I recommend are:

Recovery Force
Data Medics
Data Savers
PC Image
Data Busters
Mind Merge

Should you want to try to recover the data on your own, you should first start by trying to get a full sector-by-sector clone of the drive with a program that can work around and log bad sectors. There are two open source linux programs I recommend for that, gnu ddrescue and hdd superclone. Once you have the drive cloned, you can then attempt to recover the data from the clone using various data recovery programs of your choice. My preferred program to recommend is R-Studio, but others should work too.