I don't know where you are in Colorado, but I found this on the Weld County DMV page. I would assume that the process is the same throughout the state.
What do I do if my license plate is lost, stolen or damaged?
To replace license plates, you must bring your registration and any remaining plate (for example, if only one plate in a set of two is lost, stolen, or damaged) to our office. The fee is $5.00 plus material fees of up to $3.54 to replace regular plates and $14.00 plus material fees of up to $5.36 to replace designer plates. With personalized plates both plates need to be surrendered, otherwise you will need to wait 12 months to apply for new plates. In the case of a lost or stolen plate, notify a City, County or State law enforcement agency, and bring in a copy of the report to our office. http://www.co.weld.co.us/departments/clerkrecorder/motorv/services_faqs.htmlGood luck! :hi: