Partition shows up, but can`t access,"not formatted"

[B A T M A N]

Saturday, scanned my 2 drives and defragged them both, all went well.
Sunday, only accessed my backup partition on my 2nd drive, all was well.
Today, tried to access my Games partition on my 2nd drive and it wont let
me, it says the drive isn't formatted?????? Can still access the other
partition though. Any ideas?

Partition shows up in my computer but if I try to access it, it says
"not formatted"
Not bothered about the lost files, most of them are backed up, I am more
concerned about the cause of it.

 

[Rod Speed]

Saturday, scanned my 2 drives and defragged them both, all went well.
Sunday, only accessed my backup partition on my 2nd drive, all was
well. Today, tried to access my Games partition on my 2nd drive and
it wont let me, it says the drive isn't formatted?????? Can still
access the other partition though. Any ideas?

Partition shows up in my computer but if I try to access it, it says
"not formatted"

Not bothered about the lost files, most of them are backed up, I am
more concerned about the cause of it.

Can be anything that can corrupt the file system on the partition.

See what the SMART data shows using Everest.
http://www.majorgeeks.com/download.php?det=4181

Post the SMART report, dont just look at the OKs.