Nautilus error,cannot Launch Ubuntu

Please in recovery mode and run:

cd /home; chown -R mehman ./mehman

Then reboot

Better...

Please boot in recovery mode (press shift at boot to get choice menu) and then run:

cd /home; chown -R mehman ./mehman

Then reboot

nothing happaned,it did not fixed my netbook

please tell you still get issue to point 1) ?

I did 2 of them, first I run in recover mode, then restarted and then typed all in terminal,and then restarted,but nothing happened

if you want better help give us better info...

What are the 2 issues you still get... we cannot guess...

I entered recover mode and typed cd /home; chown -R mehman ./mehman,and then rebooted,nothing happened.
Then opened Ubuntu with errors,but I can lunch Terminal (by pressing Alt+CTRL+T),I opened Terminal and typed cd /home; chown -R mehman ./mehman,rebooted.But nothing happened,how can I fix this error?

Ok so the 1 issue is solved now please open a terminal and type

sudo apt-get -f install
sudo apt-get --fix-missing install
sudo apt-get update
sudo apt-get dist-upgrade
sudo apt-get --reinstall install ubuntu-desktop

and to reboot

sudo reboot

But cannot establish internet,because modem cannot find my lan connection.the lan light is off when I connect it to my netbook

Boot to root recovery mode and run:

chmod 1777 /tmp; reboot

Should be ok

actionparsnip, but nothing happened,I did everything as you said

Try:

chmod 755 /etc/gconf/gconf.xml.system

In root recovery mode

May also want to run:

chown -R root:root /var/lib/gdm
chmod -R 777 /var/lib/gdm

Source:
http://farukatwork.blogspot.com/2011/01/usrlibexecgconf-sanity-check-2-exited.html

ok,I am just testing it

how can open my Desktop as a window by typing in Terminal? which commands do I have to write?

It did not worked, actionparsnip

Hold shift at boot and select recovery mode, then select root. This is where all the commands I have given need to be ran...

I did it it as you said, as you know I can run terminal in my screen by pressing CTRL+ALT+T, and I want to display my Destop as a folder,and my own home directory also,how can I di these?

cd ~/Desktop

will (c)hange (d)irectory to your desktop folder.

my system cannot find usb stick and sharing folder :((

What do you mean? I thought nautilus was having an issue running. What does that have to do with USB access or sharing..

I want to install Ubuntu 11.04 to usb stick,and will try it ,then will copy all my files to 80 Gb flash,and then will format it,but I couldnot do this,because my netbook couldnot boot usb stick

Why don't you have a backup? You can access your data from liveCD as you ay