Dell does not repair monitors -- neither will most repair shops.  If the monitor is under warranty and the fault was not customer caused damage, contact Dell for replacement. If it's out of warranty, and the "broken" means that the screen is physically cracked or damaged, start shopping for a new monitor. Beyond the fact that screens are not generally available as repair parts, most monitors are assembled with adhesives -- they do not come apart for repair.  And since the screen itself is on the order of 80% or more the cost of the monitor itself, they're not economically replaceable.  The market price of these is under $200 to $400 -- just the labor alone would be half that or more, and that's ignoring the general unavailability of repair parts.
How or where can i get my 24"  lcd  gaming monitor repaired. 
Broken lcd Gaming monitors