The mods will probably move this to either the fixed blade or folder forum depending on what you've got, but the more information you can give will dictate the information you get back.
Is it a fixed blade, folder? Do you have the makers name, or is there a stamp on the tang? Pics would help immensely, and it would behoove you to read the forum rules as well. Maker sure you don't make any inquiries re. value unless/until you upgrade to a gold membership.
Winston