Go to Gerber directly through its warranty page. US coverage is a limited lifetime warranty for the original end-user purchaser or giftee, covering defects in materials and workmanship. The remedy is Gerber's choice: repair, replacement, substitution or refund.
Gerber's wording covers the giftee as well as the purchaser, which is more generous than most. If you received a Gerber as a present, you are within the covered class.
Outside North America the term is 25 years rather than lifetime.
Model, description of the fault, and photographs. Gerber excludes normal wear, sharpening, misuse and unauthorized modification, so a claim reads better when it describes ordinary use clearly.
If you have reprofiled or modified the knife, say so. It is better to find out where you stand than to have a claim unravel later.
Repair, replacement, substitution with a different model, or a refund, at Gerber's option. Substitution is common where a model has been discontinued.
Warranty terms are set by the manufacturer and can change. The maker's own warranty page, linked below, is the authority. We repeat what it says; we do not extend it, and a retailer cannot promise coverage a manufacturer has not offered.