i have windows 7, when i open any picture in photo viewer its shows coloured screen. i have scanned pc as well but there is no problem. i am attaching screen shot here as well.

You can try to use Microsoft Office Picture Manager.

Have you recently updated your graphics card driver?. if so try going back to previous driver build see if that clears that up. If not then it could be your monitors driver.

yes you are right, i am using external LCD monitor in my office. when i view pictures on laptop screen, it works perfectly but when i attach my lcd, i always face this problem. is there any solution? because in office i have to work on pictures sometime.

find support driver download for that particular brand monitor. but if it is a work monitor best to refer to company IT Tech to look into your issue and not cause yourself a problem at your place of employment.