built in iSight camera doesnt work

i've been using "amsn" mesenger and using the webcam and it's worked fine until 2 days ago now the cam closes automatically and the other person who is viewing my cam can't see me, yet a window comes up on my screen of my cam which is working fine.
Does anybody know what to do?
thank you

You havnt told us much.
Maybe try repair permissions 1st log out and then in and try it.
If you still having trouble check out iSight Trouble Shooting from 's support site

Cheers

Oh and welcome

thank you for replying and thanks for going out of your way to get the link I think i'll try find another program that supports webcam and see how that goes.
i'll report back
P.s does anybody have any suggestions on what to use - i dont have "iChat"

yahoo messenger or skype.......... they are all a bit ????, lagging behind in mac support!
Skype is probably your best bet though

ok before i even downloaded anything i went into iPhoto booth which was working fine about 20 mins ago, now when i go into it my webcam doesnt work instead theres a black screen with a small picture of a camera with a line going through it

Did you go through the link that TattooedMac Man gave you?
How to Troubleshoot iSight

yeha i went through it and i thought i found the problem but then Photo booth stopped working

ok *** now photobooth works all i did was give it some time LOL ***!
ok now its stuffed again. this is really pissing me off i'm goin to take it to the school tech guy.
Thanks for your help guys

all of it? (esp 2.)
1. See if the issue is application-specific.
Try another application (iSight works with applications like iChat, PhotoBooth, and iMovie HD 6) to see if the iSight camera exhibits the same behavior in all applications. If it only happens in one application, try reinstalling that application.

2. See if the issue is user-specific.
Test your iSight camera in another user account. If the issue only occurs in one user, the issue would be isolated to user settings.

3. Find out if the computer recognizes the iSight
Check System Profiler (in the Utilities folder, inside the Applications folder). Under the USB header, check to see if the iSight camera is detected.

4. Reset SMC or PMU
Reset your computer's SMC or PMU, and then check System Profiler again. (SMC reset instructions for iMac G5 (iSight), Intel-based iMacs; PMU reset instructions for MacBook and MacBook Pro.)

Notice how I spelled it all out just in case