Windows whithout icon to close and minimize

First couple things you can try:
1: go to System-->Preferences-->Appearance
1-1: Click on another theme to see if your icons come back
1-2: if they do click the previous theme you had and see if they stay
1-3: if they don't please post here and I can assist you further

2: in your ~ directory type "mv .gnome2 .gnome2-old"
2-1: hit ctrl+alt+Backspace to reset your settings

If these don't fix the problem, please post here

Thank you for taking the time to report this issue and helping to make Ubuntu better. Examining the information you have given us, this does not appear to be a bug report so we are closing it and converting it to a question in the support tracker. We appreciate the difficulties you are facing, but it would make more sense to raise problems you are having in the support tracker at [WWW] https://answers.launchpad.net/ubuntu if you are uncertain if they are bugs. For help on reporting bugs, see [WWW] https://help.ubuntu.com/community/ReportingBugs .

From a terminal try:

yourlogin@yourhost:~$ metacity --replace

If this works, your problem may have something to do with your video card drivers or compiz settings (note that this is just a momentarily solution, as you will probably get the same problem when you login next time.).

--Bixejo