If my trademark search shows a valid registered trademark but the owner of the trademark is no longer using the mark, can I still file?
Not if the owner has assigned or sold the trademark to another party or if the trademark is only not being used on a temporary basis. However, if the company is no longer using the trademark and has not been using the trademark for a substantial period of time (generally 2-3 years) then you may be able to successfully challenge their mark in court. Because of this they may be interested in selling the trademark to you inexpensively. But be warned, the minute you contact them they may immediately start using the mark!