I am on Debian and I have another hard drive that also has Debian on it and I was running it just few minutes ago, but now I am mounting it(/dev/hdb1) to /media/hdb1/.

So I go to /media/hdb1/home/ and am expecting to find a directory called "brynjarh", which is the home directory of a user that used the operating system on the hard drive, now it isn't there, can anyone explain why it isn't there? I haven't tried yet to run from this hard drive again but I might try that if I can't seam to find out why the directory isn't there anymore.

It sounds like you have /home on a different partition. Take a look at your fstab file on that system to see:
grep home /media/hdb1/etc/fstab

Yea, it just poped into my head that I have /home on a different partition.
So problem fixed..