Try unmounting MyDocs then running 'fsck'. There are some threads about it on TMO. Remember to run/repeat the check until no errors are reported.

Thank You.
This is what I tired in the first post.

I got the standard error that it was unmounted. fsck told me that cluster size was zero, peterleinchen recognized that as a red flag. Also mount complained about a Invalid argument.

After trying to run (backupmenu) fsck yesterday. I notice that it displays unknow file system or something like that when I reboot now. I noticed that symptom in other threads.

try this..
and reboot..

With error message the is no access on file system layer anymore. There is no mount, umount or fsck.whatsoever!

Try to copy the partition table back with the dd command i pm'ed to you to get it, hopefully, working. Or, in some cases, you could try to recover files with testdisk and then reformat the file system.

Edit: Not the partition table, but the backup of the first sector will be copied.

Given that the problem is with the FAT32 filesystem on the partition itself, i.e. not a problem with the partition table or with the rest of the system, my best bet would be to do the chkdsk under Windows (from the disk manager).

You had that even in your first post "it recognizes the N900 as Removal Disk G and H but I can't explore." Doesn't it let you check the file system for errors?

Thank You
First I want to try pusak gaoq's suggestion to download Gparted Live CD to my windows laptop. Then I'll run backupmenu (mass storage mode) and connect it to my laptop.

If that fails then If that fails then testdisk application from the package recovery-tools followed by a reformat of the file system. I assume testdisk does the reformat? Thanks for letting me know that cluster size is zero means there is no access on the file system.

@reinob
When I checked a few days ago it wouldn't let me check the file system for errors. But since yesterday's debugging produced a new unknown file system error message on reboot I'll try again.

And right you are!
It is the backup of the first sector of the partition, which should be copied with dd on low level.
I edited the above post.

Finally my N900 is back!
It was tiring of having a cell phone that can only make phone calls.

Michaaa62's code did the trick.

GParted recognized the 4 partitions but identified dev/sdb1 as unknown and flagged it as "lba" and could not do anything with it. I also tired testdrive, it found some clusters but could not do anything.

fsck got rid of most of the errors. But left one stubborn one. I let windows run all night to fix that one. And then in the morning ran fsck again, where it found and fixed a new error.

Thank You everyone for all your help.

gud to hear that you have solved your problem.....

please edit your first post in this thread & add [SOLVED] infront of your thread title....

thank you...

What would the ideal way be to repair a problematic /home/user/MyDocs partition if you have broken the USB porto on your N900?

I did
<i>
sudo umount /dev/mmcblk0p1
sudo fdisk -af /dev/mmcblk0p1
sudo fdisk -r /dev/mmcblk0p1
sudo reboot
</i>
woops, I mean (fsck not fdisk!)

sudo umount /dev/mmcblk0p1
sudo fsck -af /dev/mmcblk0p1
sudo fsck -r /dev/mmcblk0p1
sudo reboot

Curious if dosfsck does anything more, with my old zaurus I remember using e2fsck for ext2 and it being more powerful than straight fsck if my ext2 formatted SD card got hosed by a broken transfer or something

This did the trick on todays problem but I would like to know if there are further fsck or dosfsck tricks to clean out a file system when I cant use another machine for whatever reason. I know I have had better results with the Ubuntu disk utility than either my laptops fsck or gparted.