Broken Imac screen

Make a Genius Bar appointment at any Apple Store for a free evaluation. While it is possible to do it yourself, it is difficult.

Here is an exqmple on a 2013 iMac:

SOLVED: 27" Late 2013 iMac broken screen replacement ( - iMac Intel 27" EMC 2639 - iFixit

Make a Genius Bar appointment at any Apple Store for a free evaluation. While it is possible to do it yourself, it is difficult.

Here is an example on a 2013 iMac:

SOLVED: 27" Late 2013 iMac broken screen replacement ( - iMac Intel 27" EMC 2639 - iFixit

The answer varies depending on what model iMac you have. Your profile, if still accurate, indicates you are running an older iMac with Mac OS X 9.2.1. Several generations ago the early aluminum iMac's used a separate glass panel on the front of the display that is held in place with magnets. When the glass panel broke it go be replaced independent of the iMac's LCD display as long as the broken glass panel didn't physically damage the front surface of the LCD.

Newer iMac's (last 4 cycles) bond the glass panel with the LCD display. If the display on these models breaks the entire display assembly needs to be replaced which makes it an expensive repair. As macjack indicated, you'll need to take it to a service provider to get a diagnosis.