Windows 7 External drives no longer recognized

[Cosmonium]

Using Windows 7 for 9 months with two external drives. This morning, neither drive is recognized. In Disk Management, both drives appear as "Unknown," and I am advised to "initialize disk." I right click on the drive and choose to initialize disk, but the reply I get is "Invalid Function." One of these hard drives contains my backup. I have read many related posts, but not found one that is specific to my situation.

 

[Joe S]

I assume these are USB. Try disconnecting both properly reboot the system then plug the drive back in. I had one that was cranky like that and that took care of it. You may want to unplug power to the drives after you disconnect them. What make and model are they?
Joe

 

[Cosmonium]

Thanks for replying, Joe. I had already done as you suggested, but tried it again anyway. My two external drives are still only seen as "unknown" in disk manager. One of the drives is an Iomega 250GB and the other is actually an internal drive from an old computer now in a housing. I have had no problem whatsoever accessing and using these drives until now. Windows sees all other peripherals, including my iPhone.

 

[cybercore]

Using Windows 7 for 9 months with two external drives. This morning, neither drive is recognized. In Disk Management, both drives appear as "Unknown," and I am advised to "initialize disk." I right click on the drive and choose to initialize disk, but the reply I get is "Invalid Function." One of these hard drives contains my backup. I have read many related posts, but not found one that is specific to my situation.

How many primary partitions do you have? There can be four primary partitions. One of them can be an extended partition, which can contain any number of logical partitions.

​

 

[Cosmonium]

How many primary partitions do you have? There can be four primary partitions. One of them can be an extended partition, which can contain any number of logical partitions.

I have never partitioned my C drive, so it is in whatever state it came in. My recovery drive is designated D, so can I assume I have two primary partitions?

 

[cybercore]

Yes, you do, C and D. Can you see the external drives in device manager, what does it say about them in tabs "General" and "Driver"?

 

[Cosmonium]

The drivers are up to date and "device is working properly." Thanks for your help on this.

 

[Keithj]

I had the same problem, a couple of weeks ago, with two USB external drives that had been absolutely fine for several years. Windows reported no problem when I eventually managed to persuade it to read them again, but backup failed part way and they again became "unreadable". Powering down and restarting brought them back.

I suspected the Windows backup routine might be at fault, so I downloaded Paragon Backup 2010 Free. That told me that there was a problem with both drives and that they needed to be reformatted.

I deleted and recreated the partition on each, reformatted them, and they worked again fine. Paragon also says they are OK now. It was odd that both went offline the same day, after years of flawless operation, and when neither had been "used" for some days.

I don't know if a Windows 7 update did something - I seem to get an awful lot of updates these days.

I worried that they are on their way out, so I bought a brand new (fast) Verbatim 1Tb eSATA drive, but I find to my annoyance that eSATA does not work with Windows 7, so I am having to use the drive as USB. A different problem.

My suggestion would be: if there's stuff on them you need, back it up to another drive first, then repartition and reformat them.