Try following steps to install NimbuZz on Ubuntu Or Linux Mint
before doing this steps get Google Chromium as browser
1.Open this LINK in chromium browser
3. A pop up window will rise to confirm , just click ADD4. You can select the Apps from the menu in the bottom of the chrome
DO YOU NEED MORE SUPPORT CHECK THIS LINK : http://www.nimbuzz.com/en/support/
where “username” is the username of the user that you don’t know the password
Now type a new password twice and you are done!