I had this problem after the first serious use of a drill I bought (judging by the resistance, I believe I was drilling into concrete). TriedI tried using the drill in reverse and various other suggestions I saw on the internet but had no luck. What I ended up resorting to was to buy a "Draper 43863 2-Piece Soft-Grip Strap Wrench Set""Draper 43863 2-Piece Soft-Grip Strap Wrench Set" from Amazon (I think there are other brands and other vendors, which may well be as good or better). It worked a treat. Given the purchase on the keyless chuck that I managed to get, I can't think I would have been able to release the drill bit otherwise. (Retrospectively, I don't think I should have bought such a powerful drill with a keyless chuck). [PS I know this is an old thread, answer more targetted at others like me that google'd an answer for this]