Hi, I have a seagate 1tb external hardrive. when I connect to my old computer all was fine, I even connected to my sisters, it was also fine. I may have plugged in a different adaptor by accident, is this why light flashes and sometimes not at all.....can this be fixed without losing stored info???

What operating systems did you have on the computers??

click start control panel administrive tools ,computer management ,device manager look through all of your devices if you see a yellow question mark?or exclamation mark ! or red x
right click to reinstall drivers or
if you can see your usb but its not working
ports(com&lpt)right click update driver

sometimes the wires inside the cable will be damaged due to bending or stretching or placing heavy equipment upon the cable,
just replace the cable of the hard disk, when you plugged the external disk drive you got that windows could recognize the USB device change the cable everything should work fine again,

check the USB leads that attach to the motherboard usually red-white-green-black make sure they are securely seated and have no dust build up on them dust will cause static and a lot of unforeseen problems also make sure the computers Ram and Cmos battery are securely seated
if this fails to fix the problem

you might have to install a usb 2 or 3 card they are cheap and easy to install you can buy these on Ebay very cheap
click start control panel administrive tools computer management disk management right click on your drive select properties click tools you should see click check now click start two boxes automatically fix files and scan for and attempt recovery of bad sectors place then a tick in one box then select check now start or you might tick one box then return after its finished the first repair then return and tick the second box

((I have found better results ticking the first box then reurn and tick the second box)) you should not do anything while the chkdsk utility is in progress any input may damage this drive also you might need to do this

click start click to open on my computer you should see your usb drive F: right click select properties there will be an array of options select the sharing tab option then advanced sharing make sure you have a tick in the share this folder box then click permissions make sure you have full control in windows 7

click start control panel user accounts click on the administrators account if you have made one or you will have to create one in windows XP
also
If you are running a Windows XP OS then you might be able to:
click start right click on my computer select open
Right click the icon of your Flash Drive (It should be F: / E: or something)
Click Properties in the menu that comes up
Click the Sharing tab
Click permissions
And finally, click Allow next to Full Control.

if you need more help with this post a reply

hope this helps you