"A few days ago my dms stops working. it just played 1 track.... by selecting any other track my head unit (kenwood) said reading first, then eject."
How cold is it where you are running your phatbox? My 80gig Toshiba drive won't function when it is any colder than about 5 degrees c, and my 20gig VW DMS won't work below about -5 degrees c. The cold weather failure symptoms are similar to yours. When I take the DMS inside for diagnosis, I don't find significant problems (because the drive warms up).
To recover the phatbox operation after it tries and fails to boot/run a cold drive, I have to unhook the power from the Phatbox, reconnect power, and insert a warm drive.
"Now i can't load any firmware on the dms and the "check for updates" function in the phatnoise software (music manager 2.3) doesn't work."
I am having the same problem with the both Music and Media Manager software. It says "Installed Product PhatNoise Platinum Edition" (the default) and no other products are available. I can't install plugins because PMM/PMM2 won't let me select the Kenwood Phatbox, and the plugins complain they aren't compatible with the current selected setup. Does anyone know if the PMMs are reliant on the proper input from the phatnoise web site? If the site is down, can we get them to fix the site? Or is there a work around to allow firmware and head unit selection to work on PMMs again?
sbingner's reply about firmware load procedure will work for recovering the firmware and system files to the DMS you've wiped. But maybe you didn't have a corrupt DMS in the first place, maybe the drive was too cold to run.