I press w key to use move tool,when I drag the manipulator handle x(y or z)to move object(face or vertex),it moves,but after that the manipulator disappeared(look at the left tool box,it has been select tool，the arrow icon),if i want to go on moving,i have to press w key again and again.scale and rotate tool have the same problem,too.I use NURBs modeling objects these days,two days ago,everything is all right,i don’t know how it occurs.and because of that,when i use the round tool across boundary edges of two faces’ in the workspace,it failed,it just selected one NURBs face.
i have try some ways to solve it,for example:reset tool,restore the setting, delete the maya document in My documents,reinstall the maya programme,but the problem is also,it is useless.i don’t know why,can anyone help me,thanks a lot!

Maybe its a software bug or some issues with the graphics....Check whether you facing the same issue by installing a previous version of maya.If it still occurs then try the trial version which is available here.
Cheers!

everything is ok two days ago,i think there must be a software set problem

To get around this bug there’s another way to access the transformation manipulators.
Click on the Persp/Outliner layout. In the outliner view, go to panels persp view or what ever camera your using.
The Manipulators should come up. I honestly don’t think this is a graphics card related problem. It’s a scene specific issue.
I have been working on a test scene in Maya 2009 for weeks with no problem and this happened in a later scene version.
If I load an earlier version of this scene, the manipulator shows up with no problem.

You will notice if you open a brand new scene, create an object the manipulator will show until you load that scene you first discoverd the problem with.

I would report it to Autodesk so they hear it from more than one person.

Cheers,

Found another way to fix the problem. In the view your having the problem, go to the Panel menu > Tear Off ...
then close the torn off copy. The view it came from should now have the manipulators.
For some reason cameras get corrupted in the files.

I’m sorry about my poor English,but i don’t know what Panel menu > Tear Off means,can you explain exactly?
I discovered if i select an index in channel box,translate rotate or scale,the manipulator will keep normal showing.but sometimes channel box have no index to select ,i have to face that boring problem.

I would agree the graphics card issue. Make sure your graphics card:
- Has updated drivers
- Is supported by Maya. I’ve found the Quadro FX line of graphics cards to be excellent for use with Maya.

Other things to check when fixing this problem:
- Press the ‘=’ a few times… this enlarges the manipulators
- Make sure the pivots for the objects haven’t been moved to a different location
- Make sure caps lock isn’t on

If none of this works and you’re sure you have the right video card with updated drivers…
- Close Maya
- Rename your preferences folder: xxxxx_BAK
- Open Maya
This process has corrected strange bugs that Maya sometimes develops. It seems that a setting becomes corrupted in the repeated preferences saving.

I hope your problem is already fixed.

----------------------
Andrew Britton
Autodesk Certified Instructor of Maya
Lead Look Developer, Lightcraft Technology LLC
3D Course Director, http://www.IDMAonline.com
http://www.andrewbritton.com

Just found this out too....

In your “Show” menu for Persp, or ortho views… make sure “Manipulator” is checked.... unchecking this will hide your manipulators.

----------------------
Andrew Britton
Autodesk Certified Instructor of Maya
Lead Look Developer, Lightcraft Technology LLC
3D Course Director, http://www.IDMAonline.com
http://www.andrewbritton.com

All methods you suggested didn’t take effect,they are no use.also thanks!

Mine also disappeared. My solution was to:

Show>NONE

and then afterwards

Show>ALL

Even though my manipulators was checked on before i did (Show>None)

They magically appeared again when i did both Show>NONE and Show>ALL

Hope this will help for you.

I’m having the same issue but it is not all manipulators, just the manipulator tool (t) which should allow you to re-orient an object like you do a light.  It works with lights but not with polygons.  The strange thing is it worked for a while and just disappeared.  I’m on a MacPro.  No driver update.  I tried deleting user prefs and restarting.  Nothing.  Just does not work.  This is quite aggravating.  Camera select on 2009 for Mac’s does not work (backculling does which is how you have to do it) , the manipulator just goes away.

"Yesterday is History, Tomorrow a Mystery, Today is a Gift, Thats why it’s called the Present”
Kung Fu Panda

Maya 2012, PFMatchit, Nuke, Modo 501, CS5
Win 7 Pro 64bit
i7 x980 3.3Ghz, 24Gb Ram
Quadro FX3800 Driver 8.17.12.5896