I connected N900 to PC with USB Cable and choose Masstorage.
<some minutes later>
The PC got an error from a website and suddenly Shutdown.
I discharge my N900 and try to open the Main Phone Memory (32GB) with File Manager, but it can't open it.
I Restart N900 and try again, but now... when i click on Menu button, its not appear.
I plug it to PC again... The PC can't open it too. The phone isn't appear Masstorage and PC Suit buttons.

Can anyone tell me how to fix it?

without connecting the N900 to anything per USB, open xterm and type "mount" and then "df -h"

post the results, verbatim, here.

thank for your help, but i am not so good at english.
i did like your tutorial but nothing happen

- i am not plug n900 to anything
- i open x terminal
- i type mount then press enter
(more lines auto appear)
- i type df(space)-h and press enter button again
(more lines appear)
- i go to file manager to see phone memory, but it still not appear

did i wrong or something?

You need to catch the log files for those commands... Try to type mount > mount.log AND df -h > df.log
This will redirect your output to text files called "mount.log" and "df.log" that will be saved in your actual directory. Them you can copy the text files and post here.

Because i can't find the saved log files, so i write it in here:

~ $ mount
rootfs on / type rrotfs (rw)
ubi0:rootfs on / type ubifs (rw,bulk_read,no_chk_data_crc)
proc on /proc type proc (rw)
sysfs on /sys type sysfs (rw)
tmpfs on /tmp type tmpfs (rw,noatime,size=1024k)
tmpfs on /var/run type tmpfs (rw,nosuid,noatime,size=256k,moe=775)
none on /dev type tmpfs (rw,noatime,size=10240k,mode=775)
devpts on /dev/pts type devpts (rw,grid=5,mode=620)
tmpfs on /dev/shm type tmpfs (rw,nosuid,nodev,noatime,size=65536k)
/dev/mmcblk0p2 on /home type ext3 (rw,noatime,errors=continue,commit=1,data=writebac k)
/home/opt on /opt type none (bind)
nodev on /sys/kernel/debug type debugfs (0)
/dev/mmcblk1p1 on /media/mmc1 type vfat (rw,noauto,nodev,noexec,nosuid,noatime,nodiratime, utf8,uid=29999,shortname=mixed,dmask=000,fmask=013 3,rodir)
~ $ df -h
Filesystem Size Used Available Use% Mounted on
rootfs 227.9M 127.5M 96.2M 57% /
ubi0:rootfs 227.9M 127.5M 96.2M 57% /
tmpfs 1.0M 68.0k 956.0k 7% /tmp
tmpfs 256.0k 72.0k 184.0k 28% /var/run
none 10.0M 80.0k 9.9M 1% /dev
tmpfs 64.0M 4.0k 64.0M 0% /dev/shm
/dev/mmcblk0p2 2.0G 349.3M 1.5G 18% /home
/home/opt 2.0G 349.3M 1.5G 18% /opt
/dev/mmcblk1p1 950.7M 17.3M 933.4M 2% /media/mmcl
~ $

The MyDocs partition is not mounted. This often happens when the partition is unmounted unclean, and thereby the file system becomes corrupted. You need rootsh from extras repository installed for this to work:If no errors are put out, please reboot. Else post the full output here.

extras repository, is that my last hope?

nope ! Is your first option

How is installing rootsh going? I hope you do have access to Internet on your Nokia N900.
Best wishes.

i can't install extrarepostory, after add to catalog and checking for update, it not appear anything else.
i open xterminal and type "sudo gainroot" and press enter, it appears a line "enable rd mode if you want to break your device"
i fear it. do or not?