I have a toshiba external harddrive that I've had for a couple years with important data on it. Now when I plug it into my computer or laptop, a window coes up saying it nedds formatted. Will formatting it erase the data I have on it already? How can I fix this problem?
If you format the drive you will clear the information from it and set it up as a new drive.
If the drive keeps reporting it needs to be formatted, then there may be a fault with the way the information on the drive is catalogued.
Do you know how the drive is formatted (NTFS, FAT, etc.) because you may need to know this to be able to get the information back off it.
You could try running CHKDSK /F on the drive, it will insist that you restart your computer so the tests can be done on a drive not in use.
If that doesn't work you may need to get a boot disk with some DOS based disk repair tools to try to connect to the drive and repair the way the information is stored.
I would recommend trying something called Recuva from http://www.piriform.com/recuva
That will allow you to run a scan to see if there is anything on the drive you can get fairly quickly.
If the drive is reporting that you need to format it again, there might be damage done to the data on the drive.
Some of it might be damaged beyond recovery, some of it might need a little work to recover and some is completely perfect.
Generally,take data and copy,paste,drag from external h/drive to desktop internal h/drive. Then see if reformat still required either Fat 32 or NTFS;the latter is more contemporary.
Had an external harddrive not seen by d/top as crappy connection then remove external casing and plug the hard drive into a 2.5/3.5 usb sata h/d docking station
and retrived all data be sure to have conversion cable Sata & IDE to USB 2.0 cables
so lousy connectors made a brick drive.
Formatting a hard drive does not erase anything from the drive , it just makes the data that is there able to be written over. Once you write over the data then it starts to become erased but even then not completely , it can still be recovered but at a very high cost.
So on a regular hard drive that has data on it that has been formatted the data can be recovered by a program like Recuva which you can download for a free trial software. If you write over the files then it's going to cost you and generally there aren't a lot of files worth that unless it's government related or high priced company data.