I do admit my remarks were a bit curt, but accurate.
When you drop a hard drive, and you experience the symptoms you have experienced, then that is when you stop running diags and recovery programs on it and look forward to data preservation (1st priority), then recovery. I deal with this a lot on laptops, and it never ceases to amaze me that people run their damaged hard drives into the ground after initial damage, then bring them to me expecting a miracle.
As Chris posted above, it becomes expensive as someone has to disassemble the hard drive, pull the platters, and reinstall them in another housing with good heads. Vice versa, it might possible to swap out the heads/actuator into the present housing. Having a clean room is highly recommended. Just a piece of dust can wreck a head, likewise a small defect in a platter caused by a head slapping it can wreak havoc as well. Also it is usually necessary to have a matching firmware and controller to your present setup. Multiple platters- maintaining alignment is essential. Once you lose alignment, recovery just got a lot closer to impossible. It is difficult to do your own data recovery when it involves cracking open the hard drive. Swapping controller boards is fairly easy, but likely not your problem.
I have been through data recovery 2 or 3 times for clients. The cheapest job (Hitachi 2.5" laptop drive) was ~$800US, and I had one estimate go to $1200.
I am a huge believer in docking stations as they tend to not be moved around as much as enclosures.
I am a retired Ford tech. Next to Fords, any computer is a piece of cake. (The cake, its not a lie)
3770K @4.5, Corsair H100, GTX780, 16gig Samsung, Obsidian 700 (yes there is a 700)