Unfortunately I've deleted dpkg directory while removing the lock. By mistake I typed

root@sam:~$ rm -r /var/lib/dpkg

Now when I am trying to install/uninstall packages it shows me following error.

E: Could not open lock file /var/lib/dpkg/lock - open (2: No such file or directory)

What should I do now?

解决：

 

You removed 5 directories, the status file, etc. So, lets try to fix the stuff. First, create the directory:

sudo mkdir -p /var/lib/dpkg/{alternatives,info,parts,triggers,updates}

Recover some backups:

sudo cp /var/backups/dpkg.status.0 /var/lib/dpkg/status

Now, let's see if your dpkg is working (start praying):

apt-get download dpkg
sudo dpkg -i dpkg*.deb

If everything is "ok" then repair your base files too:

apt-get download base-files
sudo dpkg -i base-files*.deb

Now try to update your package list, etc.:

dpkg --audit
sudo apt-get update
sudo apt-get check

Now, let's take a deep breath. Phew. Do ls -l /var/lib/dpkg and compare with the above list. If some -old file is not present don't worry it will be there tomorrow.